Diagnosaurus
- Rabies
- Radial nerve palsy
- Rash, annular
- Rash, desquamative
- Rash, eczematous
- Rash, facial
- Rash, figurate (shaped)
- Rash, general DDx
- Rash, groin
- Rash, intertriginous
- Rash, malar
- Rash, morbilliform
- Rash, palms and soles
- Rash, scaly
- Rash and abdominal pain
- Rash and fever
- Raynaud's syndrome
- Reactive arthritis
- Rectal pain
- Rectal prolapse
- Recurrent abortion
- Recurrent pneumonia
- Recurrent respiratory tract infection
- Red eye
- Red eye, circumcorneal
- Red eye and eye pain
- Reflexes, delayed relaxation
- Reflex sympathetic dystrophy
- Reflux, gastroesophageal
- Reiter's syndrome
- Relapsing or recurrent fever
- Relapsing polychondritis
- Relative bradycardia
- Renal artery stenosis
- Renal cell carcinoma
- Renal cysts
- Renal failure, acute
- Renal failure, chronic
- Renal failure in HIV/AIDS
- Renal tubular acidosis
- Renal tumor
- Respiration, Cheyne-Stokes
- Respiratory acidosis
- Respiratory alkalosis
- Respiratory failure, acute
- Respiratory syncytial virus
- Respiratory tract infection, upper
- Respiratory tract infections, recurrent
- Restrictive cardiomyopathy
- Restrictive disease on PFTs
- Retinal artery occlusion
- Retinal detachment
- Retinal vein occlusion
- Retinitis
- Retinopathy
- Rhabdomyolysis
- Rheumatic fever, acute
- Rheumatoid arthritis
- Rhinitis
- Rickets
- Rickettsial diseases
- Right atrial enlargement, EKG
- Right axis deviation, EKG
- Right to left shunt
- Rigidity
- Ringworm, body
- River blindness
- Rocky Mountain spotted fever
- Rosacea
- Rotator cuff disorder
- RSV
- Rubella (German measles)