- Q fever, A78
- Quadricuspid aortic valve, Q23.8
- Quadrilateral fever, A78
- Quadriparesis
- Quadriplegia, G82.50
- Quadruplet, pregnancy
- Quarrelsomeness, F60.3
- Queensland fever, A77.3
- Quervain\’s disease, M65.4
- Queyrat\’s erythroplasia, D07.4
- Quincke\’s disease or edema, T78.3
- Quinsy (gangrenous), J36
- Quintan fever, A79.0
- Quintuplet, pregnancy