- 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
- 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) 051.0
- Coxa
- Coxae malum senilis 715.25
- Coxalgia (nontuberculous) 719.45
- Coxalgic pelvis 736.30
- Coxitis 716.65
- Coxsackie (infection) (virus) 079.2
- Crabs, meaning pubic lice 132.2
- Crack baby 760.75
- Cracked
