- Corticoadrenal - see condition
- Corticosexual syndrome 255.2
- Coryza (acute) 460
- Costen's syndrome or complex 524.60
- Costiveness (see also Constipation) 564.00
- Costochondritis 733.6
- Cot death 798.0
- Cotard's syndrome (paranoia) 297.1
- Cotia virus 059.8
- Cotungo's disease 724.3
- Cough 786.2
- Counseling NEC V65.40
- Coupled rhythm 427.89
- Couvelaire uterus (complicating delivery) - see Placenta, separation
- Cowper's gland - see condition
- Cowperitis (see also Urethritis) 597.89
- Cowpox (abortive) 051.01
- Coxa
- Coxae malum senilis 715.25
- Coxalgia (nontuberculous) 719.45
- Coxalgic pelvis 736.30
- Coxitis 716.65
