Might leg elevation and avoidance of poor postures provide better prophylaxis against venous thromboembolism than heparin or mechanical methods? 12 supine subjects tilted in 3° increments from 6° leg-down to 12° leg-up showed linear increase in mean peak blood velocity and reduction in calibre in the common femoral vein (colour-duplex ultrasound). Between horizontal and 6° leg-up, velocity was increased by 17% and diameter reduced by 14%. A ranking of mean peak velocities in six postures (sitting; standing; trunk raised 35° to legs which were first horizontal and then tilted up 6°; supine, first horizontal then 6° leg-up) showed significant increases in velocity between consecutive positions. © 1995.