Etiology, pathology, clinical and radiological symptoms, and course of transient synovitis of the hip was discussed on the basis of authors observation of 144 children as well as on literature. It was found that unloading the joint by staying in bed with slightly flexed hip led to subsidence of pain and return of full range of movement in 10 to 21 days. Only in older children the symptoms may persist 4 to 5 weeks. Permanent consequences of transient synovitis of the hip as elongation of the extremity and coxa magna in X-ray pictures are rarely observed. Transient synovitis of the hip seems not to have etiological links with Perthes disease.