The purpose of the present study was to evaluate the relationship between calf muscle pump dysfunction (CMD) and the presence and location of valvular incompetence. Deep vein obstruction might influence CMD, and so venous outflow resistance (VOR) was measured. VOR and calf muscle pump function were measured in 81 patients, 7-13 years after venographically confirmed lower-extremity deep venous thrombosis. The supine venous pump function test (SVPT) measures CMD, and the VOR measures the presence of venous outflow obstructions, both with the use of strain-gauge plethysmography. Valvular incompetence was measured using duplex scanning in 16 vein segments of one leg. Venous reflux was measured in proximal veins using the Valsalva manoeuvre, and in the distal veins by distal manual compression with sudden release. Abnormal proximal venous reflux was defined as a reflux time of more than 1 s, and abnormal distal venous reflux as a reflux time of more than 0.5 s. No statistically significant relationship was found between the SVPT and either the location or the number of vein segments with reflux. Of the 81 patients, only nine still had an abnormally high VOR, and this VOR showed no relationship with the SVPT. In conclusion, venous reflux has a limited effect on CMD, as measured by the SVPT. The presence of a venous outflow obstruction did not significantly influence the SVPT. Duplex scanning and the SVPT are independent complementary tests for evaluating chronic venous insufficiency.