- Rubeola (measles) (see also Measles) 055.9
- Rubeosis iridis 364.42
- Rubinstein-Taybi's syndrome (brachydactylia, short stature and intellectual disabilities) 759.89
- Rud's syndrome (mental deficiency, epilepsy, and infantilism) 759.89
- Rudimentary (congenital) - see also Agenesis
- Ruiter-Pompen (-Wyers) syndrome (angiokeratoma corporis diffusum) 272.7
- Ruled out condition (see also Observation, suspected) V71.9
- Rumination - see also Vomiting
- Runaway reaction - see also Disturbance, conduct
- Runeberg's disease (progressive pernicious anemia) 281.0
- Runge's syndrome (postmaturity) 766.22
- Runny nose 784.99
- Rupia 091.3
- Rupture, ruptured 553.9
- Russell (-Silver) syndrome (congenital hemihypertrophy and short stature) 759.89
- Russell's dwarf (uterine dwarfism and craniofacial dysostosis) 759.89
- Russell's dysentery 004.8
- Russian spring-summer type encephalitis 063.0
- Rust's disease (tuberculous spondylitis) 015.0 [720.81]
- Rustitskii's disease (multiple myeloma) (M9730/3) 203.0
- Ruysch's disease (Hirschsprung's disease) 751.3
- Rytand-Lipsitch syndrome (complete atrioventricular block) 426.0
