The value of short-term anticoagulant treatment in improving the early outcome in patients operated on for acute lower-limb ischemia has been debated and so far unproven. In this prospective randomized multi-center study, 188 such patients were randomized on admission, either to preoperative and postoperative anticoagulant medication (AC group, n = 94) or no anticoagulant treatment during the first month after surgery (O group, n = 94). Background factors were evenly distributed in the two groups, and 89% of the cases were considered as embolic. Analysis on an intention-to-treat basis showed no differences in outcome after 30 days. Good results, survivors who had amputation, and patients who died in the two groups are given respectively: AC group, 61%, 9%, 30%; O group, 65%, 11%, 24%. The results were similar in the two treatment groups also if only patients with a cardiac source of embolism were analyzed. Local bleeding complications were more common in the AC group (17% vs 2%, p less than 0.01). It is concluded that preoperative and early postoperative anticoagulant medication should not be routinely administered since such treatment is unlikely to improve the short-term results of lower-limb arterial thromboembolectomy while bleeding complications increase. The possible value of late (beyond 1 month) long-term anticoagulant treatment remains to be studied.