A retrospective review was made of roentgenograms from 30 patients with idiopathic osteoarthrosis of the hip. The roentgenograms were taken before the onset or very early in the course of the disease. Nine measurements were made on the anteroposterior and cross-table lateral roentgenograms. These were compared to 54 hips from normal patients. Twenty-nine of 30 patients had abnormal measurements, with as many as seven in a single individual, when compared to normal patients. There were no abnormalities in the control group. The availability of lateral views allowed an additional dimension to be added to previous studies in the literature. This study lends further support to the biomechanical theory of the etiology of idiopathic osteoarthrosis of the hip.