The efficacy and safety of recombinant tissue-type plasminogen activator (rt-PA) was evaluated in 46 patients with thrombembolic arterial occlusions in leg arteries, rt-PA was given over 1-4 h with a maximum dose of 18 mg. The effect of rt-PA treatment was determined as patency of the occluded arteries in 44 different patients 14 days after treatment. In 41 patients at least one artery was recanalized (93%) by rt-PA, and in almost half of these patients (48%) no residual stenosis were detected after the lyric treatment. A slight residual stenosis was detected in 29% of the patients and a severe residual stenosis in 21%. An additional treatment with percutaneous transluminal angioplasty was performed in 23 of the 44 patients and successful in 21 (91%). In 8 patients an addition catheter-embolectomy was performed. No difference in patency rate was detected between patients with thrombotic and those with embolic occlusions. The age of the occlusion influenced the patency rate; occlusions under the age of 5 weeks showed a patency rate of 96% compared to 82% in older occlusions. The length of the occlusion did not have any influence on the outcome of the rt-PA treatment. From the results of this open study we conclude that a dose of up to 18 mg of rt-PA is both safe and effective in the treatment of thromboembolic occlusions in leg arteries.