The measurement of the femoral anteversion is an important factor in the practice of orthopedic surgery. The anteversion is measured by means of the axis of head and neck of the femur. In this study, widely used computed tomography method of measuring anteversion was tested on femoral necks of patients. Measurement by the manual method and image viewer of computed tomography to determine the anteversion of femoral head were carried out on both femurs. In January and February 2001, 30 patients 3 to 6 years of age were randomly selected from Seoul National University Hospital. The purpose of this paper was to introduce a new method to measure femoral anteversion angle utilizing image viewer program. This new method was more accurate and convenient than the conventional manual method. In conclusion, PACS of image viewer program was statistically more reliable in determining the angle of the femoral anteversion.