We report a case of mycotic aneurysm of the ileocolic artery due to Streptococcus bovis endocarditis and acute septicemia complicated by active hemorrhage, that was treated successfully with transcatheter embolization and subsequent intravenous antibiotic treatment. This case suggests that a mycotic aneurysm can be treated successfully by percutaneous embolization in an emergent situation (active bleeding, septicemia) even without previous antibiotic therapy.