- Slate-dressers' lung 502
- Slate-miners' lung 502
- Sleep
- Sleeping sickness 086.5
- Sleeplessness (see also Insomnia) 780.52
- Slipped, slipping
- Slocumb's syndrome 255.3
- Sloughing (multiple) (skin) 686.9
- Slow
- Slowing
- Sluder's neuralgia or syndrome 337.0
- Slurred, slurring, speech 784.5
- Small, smallness
- Small-for-dates (see also Light-for-dates) 764.0
- Smallpox 050.9
- Smith's fracture (separation) (closed) 813.41
- Smith-Lemli-Opitz syndrome (cerebrohepatorenal syndrome) 759.89
- Smith-Magenis syndrome 758.33
- Smith-Strang disease (oasthouse urine) 270.2
- Smokers'
- Smoking complicating pregnancy, childbirth, or the puerperium 649.0
- Smothering spells 786.09