| 1. | Gallbladder Diseases (7 recruiting studies) |
| 2. | Gallbladder Neoplasms (7 recruiting studies) |
| 3. | Gambling (4 recruiting studies) |
| 4. | Ganglion Cysts (48 recruiting studies) |
| 5. | Gangliosidoses (1 recruiting study) |
| 6. | Gangliosidosis GM1 (1 recruiting study) |
| 7. | Gastrinoma (5 recruiting studies) |
| 8. | Gastroenteritis (25 recruiting studies) |
| 9. | Gastroesophageal Reflux (2 recruiting studies) |
| 10. | Gastrointestinal Diseases (256 recruiting studies) |
| 11. | Gastrointestinal Hemorrhage (2 recruiting studies) |
| 12. | Gastrointestinal Neoplasms (207 recruiting studies) |
| 13. | Gaucher Disease (7 recruiting studies) |
| 14. | Genetic Diseases, Inborn (167 recruiting studies) |
| 15. | Genetic Diseases, X-Linked (23 recruiting studies) |
| 16. | Genital Diseases, Female (309 recruiting studies) |
| 17. | Genital Diseases, Male (364 recruiting studies) |
| 18. | Genital Neoplasms, Female (160 recruiting studies) |
| 19. | Genital Neoplasms, Male (163 recruiting studies) |
| 20. | Germinoma (6 recruiting studies) |
| 21. | Gestational Trophoblastic Neoplasms (10 recruiting studies) |
| 22. | Giant Cell Myocarditis (2 recruiting studies) |
| 23. | Giardiasis (1 recruiting study) |
| 24. | Glaucoma (15 recruiting studies) |
| 25. | Glaucoma, Angle-Closure (1 recruiting study) |
| 26. | Glaucoma, Open-Angle (10 recruiting studies) |
| 27. | Glioblastoma (82 recruiting studies) |
| 28. | Glioma (135 recruiting studies) |
| 29. | Glioma, Subependymal (14 recruiting studies) |
| 30. | Gliosarcoma (61 recruiting studies) |
| 31. | Glomerulonephritis (9 recruiting studies) |
| 32. | Glomerulonephritis, Membranous (2 recruiting studies) |
| 33. | Glomerulosclerosis, Focal (4 recruiting studies) |
| 34. | Glucagonoma (2 recruiting studies) |
| 35. | Glucose Intolerance (4 recruiting studies) |
| 36. | Glucose Metabolism Disorders (66 recruiting studies) |
| 37. | Glucosephosphate Dehydrogenase Deficiency (1 recruiting study) |
| 38. | Glycogen Storage Disease (1 recruiting study) |
| 39. | Glycogen Storage Disease Type II (1 recruiting study) |
| 40. | Gonadal Disorders (114 recruiting studies) |
| 41. | Gonadal Dysgenesis (2 recruiting studies) |
| 42. | Gout (1 recruiting study) |
| 43. | Graft Occlusion, Vascular (1 recruiting study) |
| 44. | Graft vs Host Disease (42 recruiting studies) |
| 45. | Gram-Negative Bacterial Infections (7 recruiting studies) |
| 46. | Gram-Positive Bacterial Infections (25 recruiting studies) |
| 47. | Granuloma (12 recruiting studies) |
| 48. | Granulomatous Disease, Chronic (6 recruiting studies) |
| 49. | Growth Disorders (3 recruiting studies) |
| 50. | Guillain-Barre Syndrome (1 recruiting study) |
