Successful nonsurgical treatment of gastrointestinal bleeding and arteriovenous malformations by embolization techniques has been previously documented. 1) Compressed Ivalon sponge was found to be a suitable embolic material in animals and in four patients. 2) The material has been extensively used in surgery, and its biocompatibility has been proved. 3) Expansion of the compressed sponge to its original size after embolization makes this material extremely effective. Recanalization did not occur in animals and humans. 4) For the occlusion of larger arteries, Ivalon can be wrapped around the guidewire. Ivalon sponge absorbs blood and serum, unwraps itself allowing withdrawal of the guidewire. 5) Embolization procedures are not without risk since reflux of embolic material may occur. Therefore, these procedures have to be carried out under fluoroscopic control.