We studied 80 patients who were older than 50 years of age to determine if graded elastic compression stockings reduced the frequency of postoperative thrombosis in patients undergoing dextran 70 prophylaxis. All of the patients received a total of 2,000 mL of dextran 70 during three days; according to a random table, each of the patients had one leg encased in a graded compression stocking for one week. Thrombosis development was screened with the fibrinogen I 125 test. Eight patients manifested thrombosis-one in the thigh and seven in the calf--localized to the unstockinged leg, a frequency significantly greater than the zero frequency in the stockinged leg. No untoward effects of this combination prophylaxis were noted.