- Labyrinthitis
- Lactose Intolerance
- Laryngitis
- Latex Allergy
- Lazy Eye (Amblyopia)
- Lead Poisoning
- Legg-Calve-Perthes Disease
- Legionnaires' Disease
- Leptomeningeal Disease
- Leukemia
- Leukoplakia
- Lewy Body Dementia
- Lice
- Lichen Nitidus
- Lichen Planus
- Lichen Sclerosus
- Lip Cancer
- Lipoma
- Listeria Infection
- Liver Cancer
- Liver Disease
- Liver Hemangioma
- Lobular Carcinoma in Situ
- Low Sex Drive In Women
- Low Sperm Count
- Lung Cancer
- Lupus
- Lupus Nephritis
- LVH
- Lyme Disease
- Lymphedema
- Lymphocytic Leukemia
- Lynch Syndrome