- Clinical research investigation (control) (participant) V70.7
- Clinodactyly 755.59
- Clitoris - see condition
- Cloaca, persistent 751.5
- Clonorchiasis 121.1
- Clonorchiosis 121.1
- Clonorchis infection, liver 121.1
- Clonus 781.0
- Closed bite 524.20
- Closed surgical procedure converted to open procedure
- Closure
- Clot (blood)
- Clotting defect NEC (see also Defect, coagulation) 286.9
- Clouded state 780.09
- Clouding
- Cloudy
- Clouston's (hidrotic) ectodermal dysplasia 757.31
- Club hand (congenital) 754.89
- Clubbing of fingers 781.5
- Clubfinger 736.29
- Clubfoot (congenital) 754.70
- Clubnail (acquired) 703.8