Idiopathic chondrolysis of the hip is a rare disease in which gradual necrosis of the hyaline cartilage covering the femoral head and acetabulum leads to joint space narrowing and motion restriction. Pain, motion range limitation, and radiographic joint space narrowing are the main manifestations. We report 2 cases in 15-year-old girls, one black and the other Caucasian. Unexplained pain and motion restriction in the left hip were the presenting manifestations. Narrowing of the hip joint space was noted on standard radiographs. Magnetic resonance imaging showed a joint effusion in 1 patient and unevenness of the femoral head contour in the other. Laboratory tests including microbiological studies were normal or negative. Nonspecific synovitis was found in biopsy specimens. Immobilization and traction were the main components of the treatment strategy.