PURPOSE: To evaluate the efficacy and safety of preoperative embolization of intrancranial meningioma. MATERIALS AND METHODS: We retrospectively reviewed intrancranial meningioma patients (n=37) who underwentpreoperative embolization. They were categorized into two groups, skull base lesions (n=22) and non-skull baselesions (n=15), according to tumor location. In addition, embolization results were classified by comparisonbetween pre- and post-embolization angiography as complete (residual tumor staining < 10 or 30 %) or incomplete(residual tumor staining >or= 10 or 30%). In each group, estimated blood loss (EBL) was estimated by amount ofintraoperative transfusion with pre- and post-operative hemoglobin level. Tumor resectability was evaluated byfollow-up computed tomography. New symptoms occurring within 24 hours of embolization were considered to be thoseassociated with embolization ; symptoms improved by conservative treatment were regarded as mild, while thoseresulting in new deficits were considered severe. RESULT: In the group with skull base lesions (n=22), completeembolization with the criteria of residual tumor staining of less than 30% was performed in 14 patients(EBL=1770ml;complete surgical removal in nine patients and incomplete removal four). Incomplete embolization wasperformed in eight patients (EBL=3210ml; complete and incomplete removal each in four patients). In the group withnon-skull base lesions, complete embolization with the criteria of residual tumor staining of less than 10% wasperformed in five patients (EBL=970ml) and incomplete embolization in ten (EBL=2260ml). Complete tumor removal waspossible in this group regardless of the completeness of preoperative tumor embolization. In a case ofintraventricular meningioma (3%), intratumoral hemorrage occurred on the day following embolization. Other mildpost-embolization complications occurred in three cases (8%). CONCLUSION: Preoperative embolization can be aneffective and safe procedure for meningioma and may reduce intraoperative blood loss. Its effectiveness may dependon tumor location and the degree of embolization, though the procedure seems to be helpful for lseions at theskull base.