- Sphincter - see condition
- Sphincteritis, sphincter of Oddi (see also Cholecystitis) 576.8
- Sphingolipidosis 272.7
- Sphingolipodystrophy 272.7
- Sphingomyelinosis 272.7
- Spicule tooth 520.2
- Spider
- Spiegler-Fendt sarcoid 686.8
- Spielmeyer-Stock disease 330.1
- Spielmeyer-Vogt disease 330.1
- Spina bifida (aperta) 741.9
- Spindle, Krukenberg's 371.13
- Spine, spinal - see condition
- Spiradenoma (eccrine) (M8403/0) - see Neoplasm, skin, benign
- Spirillosis NEC (see also Fever, relapsing) 087.9
- Spirillum minus 026.0
- Spirillum obermeieri infection 087.0
- Spirochetal - see condition
- Spirochetosis 104.9
- Spitting blood (see also Hemoptysis) 786.30
- Splanchnomegaly 569.89
- Splanchnoptosis 569.89