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| Abandoned children | Ivo of Kermartin, Jerome Emiliani |
| Abbeville, France | Wulfram of Sens |
| Abdominal pains | Erasmus (Elmo) |
| Abingdon, England | Edmund Rich of Abingdon |
| Abortion, protection against | Catherine of Sweden |
| Abruzzi region of Italy | Gabriel of Our Lady of Sorrows |
| Abuse victims | Adelaide, Agostina Pietrantoni, Fabiola, Germanize Cousin, Godelieve, Jeanne de Lestonnac, Jeanne Marie de Maille, John Baptist de la Salle, Laura Vicuna, Margaret the Barefooted |
| Academies, Roman Catholic | Thomas Aquinas |
| Acadians, Cajuns | Our Lady of the Assumption |
| Accommodations | Gertrude of Nivelles |
| Accountants | Matthew |
| Accused (falsely) | Raymond Nonnatus |
| Achaia | Andrew, Apostle |
| Actors | Genesius, Vitas |
| Actresses | Pelagia |
| Adopted children | Clotilde, Thomas More, William of Rochester |
| Advertisers, advertising | Bernardine of Siena |
| Advocates | Ivo of Kermartin |
| Affianced couples, betrothed couples, engaged couples | Ambrose Sansedoni of Siena, Valentine |
| Africa, Central | The Most Pure Heart of Mary |
| Africa, North | Cyprian of Carthage |
| Africa, Southern | Mary, on feast of her Assumption |
| African Catholic Youth Action | Charles Lwanga |
| Against bad weather | Eurosia, Medard |
| Against battle | Florian |
| Against birth complications | Ulric |
| Against blight | Urban of Langres |
| Against bruises and bruising | Amalburga |
| Against caterpillars | Magnus of Fussen |
| Against chilblains | Basilissa, Genesius of Arles |
| Against cold or cold weather | Maurus, Sebaldus |
| Against cramps | Cadoc of Llancarvan, Maurice, Pancras |
| Against death by artillery | Barbara |
| Against diseased cattle | Beuno, Erhard of Regensburg, Roch, Sebastian |
| Against dizziness or vertigo | Ulric |
| Against earaches | Cornelius, Polycarp of Smyrna |
| Against enemy plots | Drausinus |
| Against egotism, aka Saint Antony's fire | Antony the Abbot |
| Against eruptions of Mount Etna | Agatha |
| Against evil spirits | Agrippina, Quirinus |
| Against famine | Walburga |
| Against frenzy | Denis, Peter the Apostle, Ulric |
| Against frost | Urban of Langres |
| Against gout; gout sufferers | Andrew, Apostle, Coloman, Gerebernus, Gregory the Great, Killian, , Maurus, Totnan |
| Against hanging; hanged people | Colman of Stockerau |
| Against hesitation | Joseph |
| Against hoarseness | Bernardine of Siena, Maurus |
| Against impenitence | Barbara, Mark the Evangelist |
| Against indiscretions | John Nepomucene |
| Against inflammatory diseases | Benedict |
| Against insects | Dominic of Silos |
| Against jealousy | Elizabeth of Portugal |
| Against kidney disease | Benedict, Drogo, Margaret (or Marina) of Antioch, Valentine |
| Against mine collapse | Barbara |
| Against miscarriages | Catherine of Siena, Catherine of Sweden, Eulalia |
| Against moles | Ulric |
| Against nettle rash | Benedict |
| Against nightmares | Raphael the Archangel |
| Against oversleeping | Vitus |
| Against pain; cures from pain; pain relief | Madron |
| Against perjury | Felix of Nola, Pancras |
| Against physical spouse abuse; victims of spouse abuse (physical) | Rita of Cascia |
| Against poison | Benedict, John the Apostle, Pirmin |
| Against poverty or impoverishment | Agostina Pietrantoni, Anne, Armogastes, Bernadette of Lourdes, Cuthman, Germaine Cousin, Julia of Billiart, Macrina the Elder, Marguerite Bourgeous, Margaret of Castello |
| Against ruptures | Drogo, Florentius of Strasburg, Osmund |
| Against scurf | Genesius of Arles |
| Against shipwrecks | Anthony of Padua, Jodocus |
| Against snakes | Dominic of Sora, Hilary of Poitiers, Magnus of Fussen, Patrick, Paul, Apostle, Pirmin |
| Against starving or starvation; starving people | Anthony of Padua |
| Against stiff neck | Ursicinus of Saint-Ursanne |
| Against sudden death | Aldegundis, Andrew Avellino, Barbara, Christopher |
| Against temptations | Angela of Foligno, Benedict, Catherine of Bologna, Catherine of Genoa, Catherine of Siena, Elizabeth of Schonau, Eustochium of Padua, Gemma Galgani, Helen del Cavalcanti, Margaret of Cortona |
| Against the devil | Dionysius the Aeropagite |
| Against twitching | Bartholomew the Apostle, Cornelius |
| Against typhus, against typhoid | Adelard |
| Against ulcers; ulcer sufferers | Charles Borromeo, Job |
| Against vanity | Rose of Lima |
| Against verbal spouse abuse; victims of spouse abuse (verbal) | Anne Marie Taigi, Godelieve, Monica |
| Against whooping cough | Blaise, Winoc |
| Against witchcraft | Benedict |
| Agirone, Sicily | Philip of Agirone |
| Agricultural workers; farm workers; farmers; field hands; field workers; husbandmen; ranchers | Benedict, Bernard of Vienne, Eligius (Eloi), Isidore the Farmer, Notburga, Phocas the Gardener, Walstan |
| AIDS care-givers | Aloysius Gonzaga |
| AIDS patients | Aloysius Gonzaga, Peregrine Laziosi, Therese of Lisieux |
| Air crew | Our Lady of Loreto |
| Air crew, Belgian | Our Lady of Loreto |
| Air crew, French | Mary, on feast of her Assumption |
| Air crew, Spanish | Our Lady of Loreto |
| Air force, Argentinean | Our Lady of Loreto |
| Air travelers | Joseph of Cupertino |
| Airborne (Paratroopers) | Michael the Archangel |
| Alabama USA | Our Lady of the Gulf |
| Alaska USA | Our Lady of the Kodiak and the Islands |
| Albania | Mary, Mother of Good Counsel |
| Albi, France | Cecilia |
| Alcala, Spain | Justus and Pastor |
| Alcira, Valencia, Spain | Bernard, Gracia, Mary |
| Alcoholism | John of God, Martin of Tours, Monica, Urban of Langres |
| Alessandro, Italy | Trifone |
| Alexandria, Egypt | Cyril of Alexandria |
| Alexians | Alexius |
| Alezio, Italy | Our Lady of the Assumption |
| Algeria | Cyprian of Carthage |
| Alpine troops | Maurice |
| Alpinists | Bernard of Montjoux (or Menthon) |
| Altar servers | John Berchmans |
| Amalfi, Italy | Andrew, Apostle |
| Ambassadors, Argentinean | Gabriel the Archangel |
| Ambulance drivers, emergency medical technicians, EMTs, paramedics | Michael the Archangel |
| American Indians, Native Americans | Anthony of Padua |
| Americas | Our Lady of Guadalupe, Rose of Lima |
| Ammunition/Ordnance /explosive workers | Erasmus (Elmo) |
| Amputees | Anthony of Padua, Antony the Abbot |
| Ancona, Italy | Judas Cyriacus |
| Andalusia | John of Avila |
| Anderlecht, Belgium | Guy of Anderlecht |
| Andorran security forces | Our Lady Help of Christians |
| Anesthetists | Rene Goupil |
| Angina sufferers | Swithbert |
| Angola | The Most Pure Heart of Mary |
| Animal welfare societies, humane societies | Francis of Assisi |
| Animals | Francis of Assisi, Nicholas of Tolentino |
| Animals, danger from | Vitus |
| Animals, domestic | Antony the Abbot |
| Antioch | Barnabas |
| Antwerp, Belgium | Walburga |
| Aosta, Italy | Gratus of Aosta |
| Apologists | Catherine of Alexandria, Justin Martyr, Thomas Aquinas |
| Apoplexy (Strokes) | Andrew Avellino |
| Apostleship of Prayer | Francis Xavier |
| Apothecaries | Cosmas and Damian |
| Appendicitis | Erasmus (Elmo) |
| Apple orchards | Charles Borromeo |
| Apprentices | John Bosco |
| Aquila, Italy | Maximus of Aquila |
| Arabia | Our Lady of Arabia |
| Aragon, Spain | Agathoclia, Braulio, George |
| Archaeologists | Damasus |
| Archdiocese of Baltimore, Maryland, USA | Immaculate Conception of Mary |
| Archdiocese of Boston, Massachusetts, USA | Patrick |
| Archdiocese of Chicago, Illinois, USA | Immaculate Conception of Mary |
| Archdiocese of Cincinnati, Ohio, USA | Albert the Great, Francis de Sales, Robert Bellarmine |
| Archdiocese of Cracow Poland | Stanislaus of Cracow |
| Archdiocese of Denver, Colorado, USA | Immaculate Conception of Mary, Francis of Assisi |
| Archdiocese of Dublin, Ireland | Kevin, Lawrence O'Toole |
| Archdiocese of Dubuque, Iowa, USA | John Vianney, Raymond Nonnatus |
| Archdiocese of Indianapolis, Indiana, USA | Francis Xavier |
| Archdiocese of Louisville, Kentucky, USA | Joseph |
| Archdiocese of Miami, Florida | Our Lady of Charity, Our Lady of the Holy Rosary |
| Archdiocese of New Orleans, Louisiana, USA | Our Lady of Prompt Succor |
| Archdiocese of New York, New York, USA | Patrick |
| Archdiocese of Omaha, Nebraska, USA | Cecilia |
| Archdiocese of Philadelphia, Pennsylvania, USA | Immaculate Conception of Mary, Paul, Apostle, Peter the Apostle |
| Archdiocese of Portland, Oregon, USA | Immaculate Conception of Mary |
| Archdiocese of Saint Louis, Missouri, USA | Louis IX |
| Archdiocese of San Francisco, California, USA | Francis of Assisi |
| Archdiocese of Santa Fe, New Mexico, USA | Francis of Assisi, Immaculate Heart of Mary |
| Archdiocese of Seattle, Washington, USA | Assumption of the Virgin Mary, Immaculate Conception, Holy Angels |
| Archdiocese of Tuam, Ireland | Jarlath |
| Archers | Sebastian |
| Architects | Barbara, Thomas, Apostle |
| Architects, Italian | Benedict, Abbot |
| Architects, Spanish | Our Lady of Bethlehem |
| Archives | Laurent (Lawrence) |
| Archivists, librarians, libraries | Catherine of Alexandria, Jerome, Laurent (Lawrence) |
| Argentina | Our Lady of Lujan |
| Argentinian military chaplains | Our Lady of Lujan |
| Arizona | Our Lady of the Highways |
| Arkansas | Our Lady of the Holy Souls |
| Arm pain; pain in the arms | Amalburga |
| Armenia | Bartholomew, Gregory the Illuminator |
| Armies | Maurice |
| Armies of Jalisco, Mexico | Our Lady of Zapopan |
| Armories | Laurent (Lawrence) |
| Armourers | Barbara, Dunstan, George, Laurent (Lawrence), Sebastian |
| Arms dealers | Adrian of Nicomedia |
| Army of the Andes | Our Lady of Mt. Carmel |
| Army, Argentinian | Our Lady of Mercy |
| Army, Ecuadorian | Our Lady of Mercy |
| Arrowsmiths; fletchers | Sebastian |
| Art | Catherine of Bologna |
| Art dealers | John the Apostle |
| Artillery | Barbara |
| Artists | Luke, Catherine of Bologna, Bl (Fra) Angelico |
| Artois region | Isberga |
| Ascoli Piceno, Italy | Emidius |
| Asia Minor | John the Apostle |
| Asses | Anthony of Padua |
| Assisi, Italy | Francis of Assisi |
| Astronauts | Joseph of Cupertino |
| Astronomers | Dominic |
| Asylums (for the mentally ill) | Dymphna |
| Athletes | Sebastian |
| Attorneys, lawyers, barristers | Catherine of Alexandria, Genesius, Ivo of Kermartin, Mark the Evangelist, Raymond of Peņafort, Thomas More |
| Augsburg | Afra, Ulric |
| Australia | Our Lady Help of Christians |
| Australian military chaplains | Our Lady Help of Christians |
| Austria | Joseph,Maurice, Coloman, Leopold, Florian |
| Authority, persons in | Ferdinand III of Castile |
| Authors | Francis de Sales |
| Automobile drivers, Automobilists, motorists | Christopher, Elijah the Prophet, Frances of Rome, Sebastian of Aparicio |
| Avenay, Champagne, France | Tressan of Mareuil |
| Aviators, aviation | Our Lady of Loreto, Therese of Lisieux, Joseph of Cupertino |
| Avignon | Agricola of Avignon, Benezet |
| Aynac, France | Genistus |