Laser Doppler fluxmetry (LDF) was used to measure skin blood flux and its vasomotion, i.e. rhythmical variations in nineteen patients with post-thrombotic venous insufficiency, and in eight healthy control subjects before and after a single intermittent pneumatic compression treatment session. Following the compression treatment session skin blood flux increased and vasomotion was seen in all the patients. The transcutaneous oxygen tension also increased slightly, but significantly, from 25.4 (range 3-56) mmHg to 30.8 (range 7-61) mmHg (p less than 0.01). It is suggested that IPC treatment decreases venous distention and venous pressure thereby decreasing vasocontrictor stimulus. This seems to restore normal skin blood flow including vasomotion.