- Riboswitches
- Ribotyping
- Riboviria
- Ribozymes
- Ribs
- Ribulose 1 5 bisphosphate
- Ribulose 5 phosphate
- Rice bran
- Rice bran oil
- Richmond Agitation Sedation Scale
- Richter's hernia
- Richter's transformation
- Ricin
- Ricinine
- Ricinoleic acid
- Rickets
- Rickettsia
- Rickettsia conorii
- Rickettsia helvetica
- Rickettsia prowazekii
- Rickettsia rickettsii
- Rickettsia typhi
- Rickettsiaceae
- Rickettsiales
- Rickettsiosis
- Ridaforolimus
- Riddelliine
- Riedel's thyroiditis
- Rieger syndrome
- Rifabutin
- Rifalazil
- Rifampicin
- Rifampicin + isoniazid + ethambutol
- Rifamycin
- Rifapentine
- Rifaximin
- Rift Valley fever virus
- Right atrial enlargement
- Right atrial pressure
- Right atrium
- Right axis deviation
- Right bundle branch block
- Right common carotid artery
- Right coronary artery
- Right gastric artery
- Right gastroepiploic artery
- Right handedness
- Right heart strain
- Right hemisphere
- Right hepatic artery
- Right iliac fossa
- Right lymphatic duct
- Right pulmonary artery
- Right sided aortic arch
- Right subclavian artery
- Right to Know
- Right to die
- Right to health
- Right to left shunt
- Right to life
- Right upper quadrant
- Right ventricle
- Right ventricular hypertrophy
- Righting reflex
- Rigidity
- Rigler's triad
- Rigor mortis
- Rikenellaceae
- Rilmenidine
- Rilonacept
- Rilpivirine
- Riluzole
- Rima glottidis
- Rimantadine
- Rimexolone
- Rimonabant
- Rinderpest
- Ring enhancing lesion
- Ring structure
- Ring vaccination
- Ringer solution
- Ringer's lactate
- Ringworm
- Rinne test
- Riociguat
- Risankizumab
- Risdiplam
- Risedronic acid
- Risk benefit analysis
- Risk communication
- Risk factors
- Risk factors for breast cancer
- Risk management
- Risk management plan
- Risk mitigation
- Risk of infection
- Risk of mortality
- Risk stratification
- Risk-reducing surgery
- Risky sexual behavior
- Risorius
- Risperidone
- Risser sign
- Ristocetin
- Ristocetin induced platelet aggregation
- Ristocetin-induced platelet aggregation
- Ritalinic acid
- Ritanserin
- Ritodrine
- Rituximab
- Rivastigmine
- Rizatriptan
- RoGFP
- Road rash
- Road traffic
- Robenidine
- Roberts syndrome
- Robertsonian translocation
- Robinia pseudoacacia
- Robinow syndrome
- Robot ethics
- Robotic surgery
- Robotics
- Rockall score
- Rocker bottom foot
- Rocker-bottom feet
- Rocuronium
- Rod and Frame Test
- Rod cells
- Rod cone dystrophy
- RodA
- Rodenticide
- Rodenticides
- Roentgen
- Rofecoxib
- Roflumilast
- Rokitansky Aschoff sinuses
- Rolandic epilepsy
- Rolapitant
- Role model
- Role-playing
- Rolfing
- Rolipram
- Rolling circle replication
- Romano-Ward syndrome
- Romberg's test
- Romidepsin
- Romiplostim
- Romosozumab
- Rongeur