The use of the A-V Impulse System of foot pumps and graduated compression stockings to reduce the incidence of thrombo-embolic disease after total hip arthroplasty is well recognised. It is not known if they have a synergistic effect as all clinical trials have used them in combination. We examined the effect compression stockings had on the ability of the A-V Impulse System to accelerate peak venous velocities in the common femoral vein in ten healthy volunteers using a duplex scanner. The use of foot pumps without stockings produced the greatest increase in peak venous velocity and this was 34% greater than using a foot pump with stockings. It is not known if this difference could account for a reduction in thrombo-embolic episodes and so we propose a randomised clinical trial.