The long-term clinical and physiological sequelae of venographically diagnosed, asymptomatic postoperative venous thrombosis were studied in a group of 51 patients following total hip or total knee arthroplasty. After a mean follow-up period of 49.7 months, the patients were recalled for interview, physical examination, air plethysmography (APG), and photoplethysmography (PPG). At the time of follow-up examination, legs with prior postoperative venous thrombosis were not more likely to have clinical findings of deep venous insufficiency than legs with a negative venogram. Abnormal venous emptying, as measured by APG, was significantly correlated (p less than 0.005) with postoperative venous thrombosis and was found in patients with both proximal and calf vein thrombi, but was not clearly associated with symptoms. There was, however, a significant correlation (p less than 0.0005) between clinical findings of venous insufficiency and incompetent valves, as reflected by rapid refilling time after exercise shown by PPG. The findings indicate that asymptomatic postoperative venous thrombosis involving calf or proximal veins can lead to abnormal vein function, but is not closely correlated with later development of symptoms. These observations also suggest that symptomatic venous insufficiency is more closely associated with calf vein valve incompetence than with proximal vein obstruction.