Transient synovitis is characterized by the development of pain arising from the hip and often felt in the thigh or knee in children between the ages of 2 and 12 years. The benign self-limiting nature of this condition has made it difficult to establish the caus'e. However, the condition is generally conceded to be the commonest cause of a painful hip in childhood. The disease is of interest, not because of its disabling condition, but because of the difficulty in differentiating it from more serious diseases of the hip, such as tuberculosis, osteomyelistis, or Legg-Perthes disease. The author had studied the clinical symptoms and signs, roentgenologic findings, and treatment of the 34 patients who had admitted to Severance Hospital Yonsei Medical Center in Seoul, Korea from January 1970 to December 1979, under the diagnosis of the transient synovitis of the hip and summerized the results as follows; 1. There was probably associated with predisposing factors such as infection and allergy. 2. Among the 34 patients, 28 cases(82.4%) were male and 6 cases(17.6%) were female. The most prevalent age were between 6 and 10 years old. 3. Pain and limitation of motion of the hip joint were the most common symptoms. In 56.5% of the patients, roentgenographic findings were positive. In 50% of the patients, the erythrocyte sedimentation rates were increased. 4. The treatment was conservative including bed rest, skin traction on the affected leg, non-weight bearing, antibiotics, and sedatives. Most of all patients had improved symtoms and signs within two weeks of treatment. 5. The course of this condition was short and benign with complete resolution. The occasional hip with chronic or recurrent symptoms could be distinguished from Legg-Perthes disease by the short history, normal radiographs, and the complete resolution.