- Weil's disease (leptospiral jaundice) 100.0
- Weill-Marchesani syndrome (brachymorphism and ectopia lentis) 759.89
- Weingarten's syndrome (tropical eosinophilia) 518.3
- Weir Mitchell's disease (erythromelalgia) 443.82
- Weiss-Baker syndrome (carotid sinus syncope) 337.01
- Weissenbach-Thibierge syndrome (cutaneous systemic sclerosis) 710.1
- Wen (see also Cyst, sebaceous) 706.2
- Wenckebach's phenomenon, heart block (second degree) 426.13
- Werdnig-Hoffmann syndrome (muscular atrophy) 335.0
- Werlhof's disease (see also Purpura, thrombocytopenic) 287.39
- Werlhof-Wichmann syndrome (see also Purpura, thrombocytopenic) 287.39
- Wermer's syndrome or disease (polyendocrine adenomatosis) 258.01
- Werner's disease or syndrome (progeria adultorum) 259.8
- Werner-His disease (trench fever) 083.1
- Werner-Schultz disease (agranulocytosis) 288.09
- Wernicke's encephalopathy, disease, or syndrome (superior hemorrhagic polioencephalitis) 265.1
- Wernicke-Korsakoff syndrome or psychosis (nonalcoholic) 294.0
- Wernicke-Posadas disease (see also Coccidioidomycosis) 114.9
- Wesselsbron fever 066.3
- West African fever 084.8
- West Nile
- Westphal-Strümpell syndrome (hepatolenticular degeneration) 275.1