- Catarrh, catarrhal (inflammation) (see also condition) 460
- Catarrhus aestivus (see also Fever, hay) 477.9
- Catastrophe, cerebral (see also Disease, cerebrovascular, acute) 436
- Catatonia, catatonic (acute) 781.99
- Cauda equina - see also condition
- Caul over face 768.9
- Cauliflower ear 738.7
- Causalgia 355.9
- Cause
- Caustic burn - see also Burn, by site
- Cavare's disease (familial periodic paralysis) 359.3
- Cave-in, injury
- Cavernitis (penis) 607.2
- Cavernositis 607.2
- Cavernous - see condition
- Cavitation of lung (see also Tuberculosis) 011.2
- Cavity
- Cavovarus foot, congenital 754.59
- Cavus foot (congenital) 754.71
- Cazenave's
- CDGS (carbohydrate-deficient glycoprotein syndrome) 271.8
- Cecitis - see Appendicitis