The purpose of this study was to evaluate the safety and efficacy of local intra-arterial fibrinolysis (LIF) in the treatment of thromboembolic MCA occlusions that occurred during angiography and/or endovascular procedures. A retrospective analysis included 14 consecutive cases of iatrogenic thromboembolic MCA occlusions, encountered between January, 1983 and December, 1994 in a single neuroradiological department. During that period, a total of approximately 12,000 cerebral angiographies and of 4,000 neuroendovascular procedures were performed. Only patients in whom vessel occlusion by an embolic agent (e.g., glue, particles) could be positively excluded were accepted. LIF was performed using standard microcatheters. The fibrinolytic agents were streptokinase or urokinase, in varying dosages. Immediate LIF resulted in a complete recanalization of the previously occluded vessel within 2 h or less in 8/14 patients, all of whom were asymptomatic at discharge. Partial recanalization was achieved in 5/14 patients. Four of these patients showed mild to moderate neurological deficits on discharge. In 1 patient, LIF was initiated 3 h after embolic occlusion of the MCA due to cerebral angiography. No recanalization was observed in this case. The patient improved from her initial status but continued to show moderate hemiparesis and aphasia. None of the patients sustained an intracranial hemorrhage due to LIF. Acute thromboembolic occlusion of the MCA is a rare consequence of angiography and endovascular therapy. LIF is a safe and effective tool in the treatment of this complication. Thus, LIF is an indispensable part of neuroendovascular procedures. The well-defined onset time and site of vessel occlusion, the angiographically charted effect of fibrinolytic therapy, and the possibility of following up these patients with angiography, MRI and clinical investigation are all factors which render this complication and its correction a unique clinical model for evaluating the benefits and limitations of LIF in the treatment of acute MCA occlusion.