- Cinchonism
- Circine herpes 110.5
- Circle of Willis - see condition
- Circular - see also condition
- Circulating anticoagulants 286.5
- Circulation
- Circulatory system - see condition
- Circulus senilis 371.41
- Circumcision
- Circumscribed - see condition
- Circumvallata placenta - see Placenta, abnormal
- Cirrhosis, cirrhotic 571.5
- Cistern, subarachnoid 793.0
- Citrullinemia 270.6
- Citrullinuria 270.6
- Ciuffini-Pancoast tumor (M8010/3) (carcinoma, pulmonary apex) 162.3
- Civatte's disease or poikiloderma 709.09
- Clam diggers' itch 120.3
- Clap - see Gonorrhea
- Clark's paralysis 343.9
- Clarke-Hadfield syndrome (pancreatic infantilism) 577.8
- Clastothrix 704.2
