- Conical
- Conjoined twins 759.4
- Conjugal maladjustment V61.10
- Conjunctiva - see condition
- Conjunctivitis (exposure) (infectious) (nondiphtheritic) (pneumococcal) (pustular) (staphylococcal) (streptococcal) NEC 372.30
- Conjunctivochalasis 372.81
- Conjunctoblepharitis - see Conjunctivitis
- Conn (-Louis) syndrome (primary aldosteronism) 255.12
- Connective tissue - see condition
- Conradi (-Hünermann) syndrome or disease (chondrodysplasia calcificans congenita) 756.59
- Consanguinity V19.7
- Consecutive - see condition
- Consolidated lung (base) - see Pneumonia, lobar
- Constipation 564.00
- Constitutional - see also condition
- Constitutionally substandard 301.6
- Constriction
- Constrictive - see condition
- Consultation V65.9
- Consumption - see Tuberculosis
- Contact
- Contamination, food (see also Poisoning, food) 005.9
