Western diets containing suboptimal Cu concentrations could be widespread. A link between marginal Cu deficiency and CVD has been suggested. The objective of the present study was to investigate the effect of Cu supplementation on both Cu status and CVD risk factors in healthy young women. Sixteen women with a mean age of 24 (sd 2) years participated in a randomised crossover study of three 4-week periods with 3-week washouts between periods. During each intervention period, subjects received 0, 3 or 6 mg elemental Cu/d as CuSO4 in addition to their habitual diet. Blood samples were taken to assess the effect of supplementation on putative markers of Cu status. The content of plasma lipids, lipoprotein (a), apo and certain haemostatic factors, as putative indices of CVD, was also analysed. Daily supplementation with 3 mg Cu significantly increased (P < 0.05) serum Cu concentration and the activity of erythrocyte superoxide dismutase, although there was no further significant increase after an intake of 6 mg Cu/d. The concentration of the fibrinolytic factor plasminogen activator inhibitor type 1 was significantly reduced (P < 0.05) by about 30 % after supplementation with 6 mg Cu/d. No other marker of Cu status or CVD risk factor was affected by Cu supplementation. The results indicate that supplementation with 3 or 6 mg Cu/d may improve Cu status in these healthy young women. Increased Cu intake could reduce the risk of CVD and atherosclerosis in man by promoting improved fibrinolytic capacity.