The relationship between a local hypercoagulable state and primary varicose veins of the lower legs was investigated by measuring the plasma levels of D-dimer (DD) and the thrombin-antithrombin-III complex (TAT) in 122 consecutive patients before treatment, and in 46 patients after surgical intervention and compression sclerotherapy. Elevated levels of DD and TAT were found in 25% and 20%, respectively, of the 122 patients, being significantly elevated in the patients with thrombophlebitis compared to the patients with no dermal symptoms, pigmentation, or stasis dermatitis. There was no significant difference in either parameter among eight groups of patients classified according to their valvular incompetence. The levels of DD and TAT were elevated before treatment in 25% and 20%, respectively, of 45 treated patients, but became significantly reduced after treatment. These results indicate that even though the local hypercoagulable state in varicose veins without thrombophlebitis is too subtle to be detected by systemic parameters such as DD and TAT, a local hypercoagulable state can be detected in a certain proportion of patients with venous stasis by these parameters.