- Serotonin syndrome 333.99
- Serous - see condition
- Sertoli cell
- Sertoli-Leydig cell tumor (M8631/0)
- Serum
- Sesamoiditis 733.99
- Seven-day fever 061
- Sever's disease or osteochondrosis (calcaneum) 732.5
- Sex chromosome mosaics 758.81
- Sex reassignment surgery status (see also Trans-sexualism) 302.50
- Sextuplet
- Sexual
- Sexuality, pathological (see also Deviation, sexual) 302.9
- Sézary's disease, reticulosis, or syndrome (M9701/3) 202.2
- Shadow, lung 793.1
- Shaken infant syndrome 995.55
- Shaking
- Shallowness, acetabulum 736.39
- Shaver's disease or syndrome (bauxite pneumoconiosis) 503
- Shearing
- Sheath (tendon) - see condition
- Shedding