- Stitch
- Stojano's (subcostal) syndrome 098.86
- Stokes' disease (exophthalmic goiter) 242.0
- Stokes-Adams syndrome (syncope with heart block) 426.9
- Stokvis' (-Talma) disease (enterogenous cyanosis) 289.7
- Stoma malfunction
- Stomach - see condition
- Stomatitis 528.00
- Stomatocytosis 282.8
- Stomatomycosis 112.0
- Stomatorrhagia 528.9
- Stone(s) - see also Calculus
- Stonecutters' lung 502
- Stonemasons'
- Stoppage
- Storm, thyroid (apathetic) (see also Thyrotoxicosis) 242.9
- Strabismus (alternating) (congenital) (nonparalytic) 378.9
- Strain - see also Sprain, by site
- Strands
- Strangulation, strangulated 994.7
- Strangury 788.1
- Straw itch 133.8