- Siemens' syndrome
- Sighing respiration 786.7
- Sigmoid
- Sigmoiditis - see Enteritis
- Silfverskiöld's syndrome 756.50
- Silicosis, silicotic (complicated) (occupational) (simple) 502
- Silicotuberculosis (see also Tuberculosis) 011.4
- Silo fillers' disease 506.9
- Silver wire arteries, retina 362.13
- Silver's syndrome (congenital hemihypertrophy and short stature 759.89
- Silvestroni-Bianco syndrome (thalassemia minima) 282.49
- Simian crease 757.2
- Simmonds' cachexia or disease (pituitary cachexia) 253.2
- Simons' disease or syndrome (progressive lipodystrophy) 272.6
- Simple, simplex - see condition
- Sinding-Larsen disease (juvenile osteopathia patellae) 732.4
- Singapore hemorrhagic fever 065.4
- Singers' node or nodule 478.5
- Single
- Singultus 786.8
- Sinus - see also Fistula
- Sinuses, Rokitansky-Aschoff (see also Disease, gallbladder) 575.8
