D
| Dairy workers | Bridgid of Ireland |
| Dalmatia | Blaise |
| Dancers | Vitus |
| Danger at sea | Erasmus (Elmo), Michael |
| Deacons | Stephen |
| Deaf | Francis de Sales |
| Death | Michael the Archangel, Margaret (or Marina) of Antioch |
| Death of children | Angela of Foligno, Clotilde, Elizabeth of Hungary, Felicity, Frances of Rome, Hedwig, Isidore the Farmer, Joaquina Vedruna de Mas, Louis IX, Perpetua |
| Death, happy | Joseph of Cupertino |
| Death, sudden | Andrew Avellino |
| Degree candidates | Joseph of Cupertino |
| Delaware, USA | Our Lady of Mercy |
| Denmark | Anskar |
| Dentists | Apollonia |
| Desperate situations | Jude, Gregory the Wonderworker, Rita of Cascia, Eustace |
| Desperate, forgotten, impossible or lost causes or situations | Jude Thaddeus, Gregory Thaumaturgus, Philomena, Rita of Cascia |
| Detraction | John Nepomucene |
| Devotees of the Sacred Heart | Margaret Mary Alacoque |
| Diabolical possession | Cyriacus, Dymphna |
| Dieticians | Martha |
| Difficult marriages | Catherine of Genoa, Elizabeth of Portugal, Fabiola, Godelieve, Gummarus, Hedwig, Helena, Louis IX, Margaret the Barefooted, Monica |
| Difficult situations | Eustace |
| Digne, France | Vincent of Digne |
| Dijon | Benignus of Dijon, Urban of Langres |
| Diocesan priests | John of Avila |
| Diocese of Achonry, Ireland | Attracta, Nathy, Attracta |
| Diocese of Albany, New York, USA | Immaculate Conception of Mary |
| Diocese of Alexandria, Louisiana, USA | Francis Xavier |
| Diocese of Antigonish, Nova Scotia, Canada | Ninian |
| Diocese of Arlington, Virginia, USA | Thomas More |
| Diocese of Austin, Texas, USA | Immaculate Conception |
| Diocese of Barbastro, Espaņa | Raymond of Barbastro |
| Diocese of Baton Rouge, Louisiana, USA | Joseph |
| Diocese of Birmingham, Alabama | Paul, Apostle |
| Diocese of Bismarck, North Dakota, USA | Immaculate Conception |
| Diocese of Bridgeport, Connecticut, USA | Augustine of Hippo |
| Diocese of Burlington, Vermont, USA | Immaculate Conception, Patrick |
| Diocese of Camden, New Jersey, USA | Immaculate Conception |
| Diocese of Charleston, South Carolina, USA | John the Baptist |
| Diocese of Cleveland, Ohio, USA | John the Evangelist |
| Diocese of Colorado Springs, Colorado, USA | Our Lady of Guadalupe |
| Diocese of Columbus, Ohio, USA | Francis de Sales |
| Diocese of Constantinople | Andrew, Apostle |
| Diocese of Corpus Christi, Texas, USA | Our Lady of Guadalupe |
| Diocese of Covington, Kentucky, USA | Paul, Apostle |
| Diocese of Crookston, Minnesota, USA | Immaculate Conception |
| Diocese of Cuenca, Spain | Julian of Cuenca |
| Diocese of Des Moines, Iowa, USA | Mary, Queen of Heaven, Pius X |
| Diocese of Dodge City, Kansas, USA | Our Lady of Guadalupe, John the Baptist |
| Diocese of Duluth, Minnesota, USA | Our Lady of the Holy Rosary |
| Diocese of Elphia | Asicus |
| Diocese of Fairbanks, Alaska, USA | Therese of Lisieux |
| Diocese of Fargo, North Dakota, USA | Assumption of the Virgin Mary |
| Diocese of Ferns, Ireland | Aeden of Ferns |
| Diocese of Fort Wayne-South Bend, Indiana, USA | Immaculate Conception |
| Diocese of Fort Worth, Texas, USA | Patrick |
| Diocese of Fresno, California, USA | Therese of Lisieux |
| Diocese of Gallup, New Mexico, USA | Our Lady of Guadalupe |
| Diocese of Gaylord, Michigan, USA | Our Lady of Mount Carmel |
| Diocese of Grand Island, Nebraska, USA | Blessed Virgin Mary |
| Diocese of Great Falls-Billings, Montana, USA | Matthias the Apostle, Pius X |
| Diocese of Green Bay, Wisconsin, USA | Francis Xavier |
| Diocese of Guadalajara, Mexico | Our Lady of Zapopan |
| Diocese of Halifax, Nova Scotia, Canada | Mary, Mother of God |
| Diocese of Harrisburg, Pennsylvania, USA | Patrick |
| Diocese of Helena, Montana, USA | Helena |
| Diocese of Hexham and Newcastle, England | Cuthbert |
| Diocese of Honolulu, Hawaii, USA | Our Lady fo Peace |
| Diocese of Jaca | Eurosius |
| Diocese of Jackson, Mississippi, USA | Peter the Apostle |
| Diocese of Jerez de la Frontera | John Grande |
| Diocese of Joliet, Illinois, USA | Francis Xavier |
| Diocese of Kalamazoo, Michigan, USA | Augustine of Hippo |
| Diocese of Killaloe | Flannan of Killaloe |
| Diocese of Lafayette, Indiana, USA | Immaculate Conception |
| Diocese of Lake Charles, Louisiana, USA | Mary Immaculate, Mother of Jesus, Peter Claver |
| Diocese of Las Vegas, Nevada, USA | Peter the Apostle, Paul, Apostle |
| Diocese of Limerick, Ireland | Munchin |
| Diocese of Lincoln, Nebraska, USA | Blessed Virgin Mary |
| Diocese of Los Angeles, California, USA | Bibiana |
| Diocese of Manchester, New Hampshire, USA | Joseph |
| Diocese of Marquette, Michigan, USA | Peter the Apostle |
| Diocese of Monterey, California, USA | Our Lady of Bethlehem, Charles Borromeo |
| Diocese of Nashville, Tennessee, USA | Joseph, Our Lady of Guadalupe |
| Diocese of New Ulm, Minnesota, USA | Mary, Mother of God |
| Diocese of Norwich, Connecticut, USA | Anne, Patrick |
| Diocese of Oakland, California, USA | Our Lady, Queen of the World |
| Diocese of Ogdensburg, New York, USA | Immaculate Conception |
| Diocese of Owensboro, Kentucky, USA | Stephen the Martyr |
| Diocese of Paterson, New Jersey, USA | John the Baptist |
| Diocese of Pensacola-Tallahassee, Florida, USA | Michael the Archangel, Thomas More |
| Diocese of Peoria, Illinois, USA | Immaculate Conception |
| Diocese of Phoenix, Arizona, USA | Our Lady of Guadalupe |
| Diocese of Pittsburgh, Pennsylvania, USA | Immaculate Conception |
| Diocese of Portland, Maine, USA | Immaculate Conception, John the Baptist, Patrick |
| Diocese of Providence, Rhode Island, USA | Our Lady of Providence, Paul, Apostle, Peter the Apostle |
| Diocese of Pueblo, Colorado, USA | Immaculate Conception of Mary, Therese of Lisieux |
| Diocese of Regensburg, Germany | Erhard of Regensburg |
| Diocese of Reno, Nevada, USA | Our Lady of the Snows |
| Diocese of Reno, Nevada, USA | Vincent de Paul |
| Diocese of Rockford, Illinois, USA | Immaculate Conception |
| Diocese of Rockville Centre, New York, USA | Agnes of Rome |
| Diocese of Ross, Ireland | Fachanan |
| Diocese of Sacramento, California, USA | Our Lady of Guadalupe, Patrick |
| Diocese of Saint Cloud, Minnesota, USA | Cloud |
| Diocese of Saint Petersburg, Florida, USA | Jude Thaddeus |
| Diocese of Salina, Kansas, USA | Our Lady of Perpetual Help, Francis of Assisi |
| Diocese of San Bernardino, California, USA | Bernardine of Siena |
| Diocese of San Diego, California, USA | Diego |
| Diocese of San Jose, California, USA | Joseph |
| Diocese of Santa Rosa, California, USA | Rose of Lima |
| Diocese of Savannah, Georgia, USA | John the Baptist, Our Lady of Perpetual Help |
| Diocese of Scranton, Pennsylvania, USA | Peter the Apostle |
| Diocese of Sens, France | Potentian, Sabinus |
| Diocese of Shreveport, Louisiana, USA | Immaculate Conception, Elizabeth Ann Seton, Peter Claver |
| Diocese of Sioux City, Iowa, USA | Our Lady of Guadalupe |
| Diocese of Spokane, Washington, USA | Immaculate Conception |
| Diocese of Springfield, Massachusetts, USA | Michael the Archangel |
| Diocese of Springfield-Cape Girardeau, Missouri, USA | Philippine Duchesne, Pius X |
| Diocese of Steubenville, Ohio, USA | Immaculate Heart of Mary |
| Diocese of Superior, Wisconsin, USA | Augustine of Hippo |
| Diocese of Sutri, Italy | Dulcissima |
| Diocese of Syracuse, New York, USA | Immaculate Conception |
| Diocese of Tucson, Arizona, USA | Augustine of Hippo |
| Diocese of Tulsa, Oklahoma, USA | Holy Family |
| Diocese of Tyler, Texas, USA | Immaculate Conception |
| Diocese of Venice, Florida, USA | Our Lady of Mercy, Mark the Evangelist |
| Diocese of Wheeling-Charleston, West Virginia, USA | Joseph |
| Diocese of Wichita, Kansas, USA | Immaculate Conception |
| Diocese of Wilmington, Delaware | Francis de Sales |
| Diocese of Worcester, Massachusetts, USA | Paul, Apostle |
| Diocese of Wurzburg | Killian |
| Diplomatic services | Gabriel the Archangel |
| Diplomats | Gabriel the Archangel |
| Disabled | Giles |
| Disappointing children | Clotilde, Louise de Marillac, Matilda, Monica |
| Disasters | Genevieve (Genofeva) |
| Discretion | John Nepomucene |
| Diseases of the eye | Raphael the Archangel, Lucy |
| Diseases, contagious | Roch, Sebastian |
| Diseases, nervous | Dymphna |
| Distillers | Louis IX, Nativity of the Blessed Virgin |
| Divorced people | Fabiola, Gummarus, Helena |
| Dock workers, longshoremen | Nicholas of Myra |
| Doctors | Luke, Cosmas and Damian, Pantaleon |
| Doctors, physicians | Cosmas and Damian, Luke the Apostle, Pantaleon, Raphael the Archangel |
| Dog bites | Hubert of Liege, Vitus, Walburga, Ubald |
| Dogs; Dog lovers; Dog fanciers | Hubert of Liege, Roch, Vitus |
| Domestic animals | Antony the Abbot, Gerlac of Valkenburg |
| Domestic workers | Zita |
| Domestic workers, maids, butlers, manservants, servants | Adelelmus, Martha, Zita |
| Dominican Republic | Our Lady of Mercy |
| Doubters | Joseph |
| Doves | Denis |
| Draguignan, France | Rosalina of Villeneuve |
| Drapers | Nativity of the Blessed Virgin |
| Drought | Genevieve (Genofeva) |
| Drought relief | Herbert, Godeberta, Solange |
| Drowning, death or danger from | Adjutor |
| Drug addiction | Maximillian Kolbe |
| Druggists (pharmacists) | Cosmas and Damian |
| Dubrovnik | Blaise |
| Duchesses | Hedwig, Ludmila |
| Dukes | Henry II |
| Durham, England | Cuthbert |
| Dyers | Maurice |
| Dyers, cloth dyers, purplers | Lydia Purpuraria, Maurice |
| Dying | Joseph, Benedict, Abbot, James the Lesser, Apostle, Lebuin (Liafwine), Maximus, Nicholas of Tolentino |
| Dying people, invoked by | Abel, Barbara, Benedict, Catherine of Alexandria, James the Lesser, Apostle, John of God, Joseph, Margaret (or Marina) of Antioch, Michael the Archangel, Nicholas of Tolentino |
| Dysentery | Lucy of Syracuse, Polycarp |
| Dysfunctional families | Eugene de Mazenod |