The authors examine the effectiveness of preoperative embolization in the treatment of rhinopharyngeal angiofibroma. In addition, they evaluate the effect various embolizing substances have in the aim of establishing what is the ideal time interval between embolization and surgery. Thirteen patients with rhinopharyngeal angiofibroma (3 were recurrences) were submitted to preoperative embolization. Of these, 4 were treated with a reabsorbable microparticulate substance (Gelfoam) while the remaining 8 were treated with non reabsorbable microparticulate substances (Ivalon, ITC contour, Terbal). The time interval between embolization and surgery ranged from a minimum of 1 day with a maximum of 4 days. The authors conclude that embolization markedly reduces blood loss during surgery, so much so that the available blood supply was not required. As regards the various embolizing substances and the time lapse between embolization and surgery, the authors feel that when using reabsorbable materials the interval should not exceed 48 hours so that the supply artery can quickly be recanalized. On the other hand, for the materials which are not reabsorbed, the time interval can exceed 48 hours but must be less than 4 days because collateral circulation can arise.