Diagnosaurus
- G6PD deficiency
- Gait disorders & falls
- Galactorrhea
- Gallstones
- Gallstones, common bile duct
- Gas gangrene
- Gastric cancer
- Gastric tumor
- Gastric ulcer
- Gastrinoma
- Gastritis
- Gastroenteritis, acute
- Gastroenteritis, chronic
- Gastroesophageal reflux disease
- Gastroparesis
- Gaucher disease
- Genital herpes
- Genital warts (condyloma acuminata)
- GERD
- Giant cell (temporal) arteritis
- Giardiasis
- GI bleeding, lower
- GI bleeding, occult
- GI bleeding, upper
- Gigantism
- Gingival hyperplasia
- Glaucoma, acute (angle-closure)
- Glaucoma, open-angle
- Glomerulonephritis
- Glomerulonephritis, pauci-immune
- Glomerulonephropathies
- Glossitis
- Glossopharyngeal neuralgia
- Glucose, decreased serum
- Glucose, increased serum
- Glucose-6-phosphate dehydrogenase deficiency
- Goiter
- Gonococcal arthritis
- Gonorrhea
- Goodpasture's syndrome
- Gout
- Granuloma inguinale
- Growth hormone, increased
- Guillain-Barré syndrome
- Gynecomastia