Rab–Rai

• Rabies
• Rabson–Mendenhall syndrome
• Radial defect Robin sequence
• Radial hypoplasia, triphalangeal thumbs and hypospadias
• Radial ray agenesis
• Radial ray hypoplasia choanal atresia
• Radiation induced angiosarcoma of the breast
• Radiation induced meningioma
• Radiation leukemia
• Radiation related neoplasm /cancer
• Radiation syndromes
• Radiation-induced brachial plexopathy
• Radiation-induced lumbosacral plexopathy
• Radiculomegaly of canine teeth congenital cataract
• Radio digito facial dysplasia
• Radio renal syndrome
• Radiophobia
• Radioulnar synostosis mental retardation hypotonia
• Radioulnar synostosis retinal pigment abnormalities
• Radio-ulnar synostosis type 1
• Radio-ulnar synostosis type 2
• Radius absent anogenital anomalies
• Raine syndrome

Ram–Ray

• Rambam Hasharon syndrome
• Rambaud–Galian syndrome
• Ramer–Ladda syndrome
• Ramon syndrome
• Ramos-Arroyo syndrome
• Ramsay Hunt paralysis syndrome
• Rapadilino syndrome
• Rapp–Hodgkin syndrome
• Rapunzel syndrome
• Rasmussen's encephalitis
• Rasmussen–Johnsen–Thomsen syndrome
• Rasmussen subacute encephalitis
• Ray–Peterson–Scott syndrome
• Raynaud's disease/phenomenon
• Rayner–Lampert–Rennert syndrome

Rea–Reg

• Reactive airway disease
• Reactive arthritis
• Reactive attachment disorder (RAD)

• Reactive attachment disorder of early childhood
• Reactive attachment disorder of infancy

• Reactive hypoglycemia
• Reardon–Hall–Slaney syndrome
• Reardon–Wilson–Cavanagh syndrome
• Rectal neoplasm
• Rectophobia
• Rectosigmoid neoplasm
• Recurrent laryngeal papillomas
• Recurrent peripheral facial palsy
• Recurrent respiratory papillomatosis
• Reductional transverse limb defects
• Reflex sympathetic dystrophy syndrome
• Reflux esophagitis
• Refractory anemia
• Refsum disease, infantile form
• Refsum disease
• Reginato–Shiapachasse syndrome
• Regional enteritis

Rei

• Reifenstein syndrome
• Reinhardt–Pfeiffer syndrome

Ren

Rep–Res

• Reperfusion injury
• Repetitive strain injury (RSI)
• Resistance to LH (luteinizing hormone)
• Resistance to thyroid stimulating hormone
• Respiratory acidosis
• Respiratory chain deficiency malformations
• Respiratory distress syndrome, adult
• Respiratory distress syndrome, infant
• Restless legs syndrome

Rev–Rey

• Revesz syndrome
• Reye's syndrome
• Reynolds–Neri–Hermann syndrome
• Reynolds syndrome

Rib–Rig

• Ribbing disease
• Richards–Rundle syndrome
• Richieri–Costa–Colletto–Otto syndrome
• Richieri–Costa–Da Silva syndrome
• Richieri–Costa–Gorlin syndrome
• Richieri–Costa–Guion–Almeida syndrome

• Richieri–Costa–Guion–Almeida acrofacial dysostosis
• Richieri–Costa–Guion–Almeida–Cohen syndrome
• Richieri–Costa–Guion–Almeida dwarfism
• Richieri–Costa–Guion–Almeida–Rodini syndrome

• Richieri–Costa–Montagnoli syndrome
• Richieri–Costa–Orquizas syndrome
• Richieri–Costa–Silveira–Pereira syndrome
• Richter syndrome
• Rickets
• Rickettsial disease
• Rickettsialpox
• Rickettsiosis
• Rieger syndrome
• Rift Valley fever
• Right atrium familial dilatation
• Right ventricle hypoplasia
• Rigid mask like face deafness polydactyly
• Rigid spine syndrome

Ril–Riv

• Riley–Day syndrome
• Ringed hair disease
• Ringworm
• Rivera–Perez–Salas syndrome