Blood flow of the calf before and immediately after treadmill exercise was measured with two venous occlusion strain-gauge plethysmographies in eight healthy male subjects; one is a venous occlusion method using a cuff (Cuff method), and another is a venous occlusion method by which the vena femoralis is pressed to 2 to 3kg/cm^2 on the anterior surface of the inguino-crural near the sulcus inguinalis by means of a pressing apparatus (Press method). The calf blood flow was determined four times at about one minute intervals using the press and cuff venous occlusion method. The cuff method was used for the first and third trials and press method following the second and fourth. Four speeds of horizontal treadmill exercise were used at 80, 100, 120 and 140m/min. Each subject performed four trials of 4 minute duration for each speed except for the highest speed (140m/min) in which only two trials were completed. The reliability of both methods was ascertained from two values determined by the same method under the same condition for all subjects. The correlation coefficient for both methods was 0.94 (P < 0.001), and no significant difference was observed between the two values. Furthermore, it was found that there was a close correlation between calf blood flow obtained by the press and cuff methods (r = 0.94, P < 0.01), and no significant difference (t = 0.94, P > 0.1) between the items was observed. From these results, it is suggested that the press method is a reliable and effective technique for measuring calf blood flow at rest and after exercise.