| 1. | Dacryocystitis (1 recruiting study) |
| 2. | Deafness (3 recruiting studies) |
| 3. | Death (3 recruiting studies) |
| 4. | Death, Sudden (2 recruiting studies) |
| 5. | Death, Sudden, Cardiac (1 recruiting study) |
| 6. | Decubitus Ulcer (1 recruiting study) |
| 7. | Deficiency Diseases (5 recruiting studies) |
| 8. | Deglutition Disorders (7 recruiting studies) |
| 9. | Delirium (62 recruiting studies) |
| 10. | Deltaretrovirus Infections (12 recruiting studies) |
| 11. | Delusions (3 recruiting studies) |
| 12. | Dementia (67 recruiting studies) |
| 13. | Demyelinating Autoimmune Diseases, CNS (18 recruiting studies) |
| 14. | Demyelinating Diseases (22 recruiting studies) |
| 15. | Dengue (1 recruiting study) |
| 16. | Dengue Hemorrhagic Fever (1 recruiting study) |
| 17. | Dental Caries (104 recruiting studies) |
| 18. | Dental Deposits (1 recruiting study) |
| 19. | Dental Plaque (1 recruiting study) |
| 20. | Depression (130 recruiting studies) |
| 21. | Depression, Involutional (25 recruiting studies) |
| 22. | Depression, Postpartum (7 recruiting studies) |
| 23. | Depressive Disorder (128 recruiting studies) |
| 24. | Dermatofibroma (9 recruiting studies) |
| 25. | Dermatomycoses (1 recruiting study) |
| 26. | Dermatomyositis (7 recruiting studies) |
| 27. | Dermoid Cyst (3 recruiting studies) |
| 28. | Developmental Disabilities (14 recruiting studies) |
| 29. | Diabetes Mellitus (76 recruiting studies) |
| 30. | Diabetes Mellitus, Experimental (1 recruiting study) |
| 31. | Diabetes Mellitus, Lipoatrophic (1 recruiting study) |
| 32. | Diabetes Mellitus, Type I (10 recruiting studies) |
| 33. | Diabetes Mellitus, Type II (76 recruiting studies) |
| 34. | Diabetes, Gestational (1 recruiting study) |
| 35. | Diabetic Angiopathies (6 recruiting studies) |
| 36. | Diabetic Foot (2 recruiting studies) |
| 37. | Diabetic Nephropathies (4 recruiting studies) |
| 38. | Diabetic Neuropathies (4 recruiting studies) |
| 39. | Diabetic Retinopathy (5 recruiting studies) |
| 40. | Diarrhea (10 recruiting studies) |
| 41. | DiGeorge Syndrome (2 recruiting studies) |
| 42. | Digestive System Abnormalities (2 recruiting studies) |
| 43. | Digestive System Diseases (433 recruiting studies) |
| 44. | Digestive System Neoplasms (311 recruiting studies) |
| 45. | Dilatation, Pathologic (1 recruiting study) |
| 46. | Diphtheria (1 recruiting study) |
| 47. | Disorders of Environmental Origin (141 recruiting studies) |
| 48. | Disorders of Excessive Somnolence (4 recruiting studies) |
| 49. | DNA Virus Infections (55 recruiting studies) |
| 50. | Down Syndrome (2 recruiting studies) |
| 51. | Drinking Behavior (2 recruiting studies) |
| 52. | Drug Toxicity (21 recruiting studies) |
| 53. | Dry Eye Syndromes (4 recruiting studies) |
| 54. | Duodenal Diseases (9 recruiting studies) |
| 55. | Duodenal Neoplasms (9 recruiting studies) |
| 56. | Dupuytren's Contracture (2 recruiting studies) |
| 57. | Dwarfism (5 recruiting studies) |
| 58. | Dysarthria (2 recruiting studies) |
| 59. | Dyskeratosis Congenita (1 recruiting study) |
| 60. | Dyskinesia, Drug-Induced (1 recruiting study) |
| 61. | Dyskinesias (13 recruiting studies) |
| 62. | Dyslexia (4 recruiting studies) |
| 63. | Dyslexia, Acquired (1 recruiting study) |
| 64. | Dysmorphic Syndromes (17 recruiting studies) |
| 65. | Dysostoses (2 recruiting studies) |
| 66. | Dyspnea (1 recruiting study) |
| 67. | Dyssomnias (19 recruiting studies) |
| 68. | Dysthymic Disorder (3 recruiting studies) |
| 69. | Dystonia (11 recruiting studies) |
| 70. | Dystonic Disorders (11 recruiting studies) |
