The authors used magnetic resonance imaging to evaluate the hip joint in patients with diastrophic dysplasia. T1- and T2-weighted images were obtained from 35 patients (25 female patients, 10 male patients) of different ages (1-39 years). The status of the joint and paraarticular soft tissues was evaluated. Hip joint congruity was good, although the joint was usually deformed. The thickness of the joint cartilage was diminished and signs of early osteoarthritis, including bone cysts and local edema, were common. The ligamentum teres was visible in only 24% of patients, suggesting abnormality of the ligamentous structures. Epiphyses were flattened or absent in all young patients. Of the 17 visible epiphyses, 7 showed avascular necrosis, indicated as a decrease in signal intensity in both T1- and T2-weighted images. It seems that proximal femoral epiphysis fails to bear normal weight pressure.