BACKGROUND Graduated compression stockings (GCS) are widely used to prevent perioperative venous thromboembolism. However, actual compression pressures of GCS on patients' legs have rarely been reported. METHODS Four different types of GCS were evaluated. Compression pressures of GCS were measured hydrostatically by using a small balloon filled with water at the ankle, the calf and the knee (proximal end) in 463 legs of surgical patients. We also compared the influence of body mass index (BMI) on compression pressures of each GCS. RESULTS No GCS ideally exerted compression of each sites of the legs while maintaining adequate pressure gradient from the ankle to the knee. It revealed that adequate compression of the calf and pressure gradient between the ankle and the calf could hardly be achieved simultaneously. In some GCS, BMI did not influence compression pressure but in the others compression tended to increase in patients with increased BMI. CONCLUSIONS As the compression characteristics of GCS are different among products, selection of GCS is important for its effective use. To select a proper GCS, measurement of actual compression pressure seems necessary.