The authors abstracted the records of 43 patients treated with intra-arterial urokinase for acute ischemic stroke to identify predictors of serious complications. Sixteen (37%) had such a complication. Higher urokinase dose (>1.5 x 10(6) U), higher mean arterial blood pressure before treatment (>130 mm Hg), basilar occlusive strokes, and severe strokes were most predictive of these complications. Although urokinase is no longer manufactured, these findings identify patients at risk for complications from other intra-arterial thrombolytics.