- Clump kidney 753.3
- Clumsiness 781.3
- Cluttering 307.0
- Clutton's joints 090.5
- Coagulation, intravascular (diffuse) (disseminated) (see also Fibrinolysis) 286.6
- Coagulopathy (see also Defect, coagulation) 286.9
- Coal miners'
- Coal workers' lung or pneumoconiosis 500
- Coalition
- Coarctation
- Coated tongue 529.3
- Coats' disease 362.12
- Cocainism (see also Dependence) 304.2
- Coccidioidal granuloma 114.3
- Coccidioidomycosis 114.9
- Coccidioidosis 114.9
- Coccidiosis (colitis) (diarrhea) (dysentery) 007.2
- Cocciuria 791.9
- Coccus in urine 791.9
- Coccydynia 724.79
- Coccygodynia 724.79
- Coccyx - see condition