A new position for photoplethysmographic (PPG) assessment of lower leg venous function is described and tested. This study aids in the selection of patients for more limited stripping operation. PPG measurements were carried out in the usual sitting position and in the supine body position on limbs with primary varicose veins. Competence of the greater saphenous vein (GSV) and incompetent perforators were evaluated by venography. Limbs with a competent GSV in the lower leg had a longer 50% venous refill time (VRT/2) in the supine body position than in the sitting position (7.6 +/- 0.6 seconds vs 5.0 +/- 0.4 seconds, p < 0.01). Limbs without incompetent perforators had a longer VRT/2 in the supine body position than in the sitting position (8.0 +/- 1.1 seconds vs 5.1 +/- 0.3 seconds, p < 0.05). PPG measurement in the supine body position gave a better separation of VRT/2s on GSV competence in the lower leg and incompetent perforators. The supine body position is recommended for assessing lower leg venous function.