Congenital arteriovenous malformation in the pelvis is uncommon, particularly in males. Therefore, this entity is difficult to diagnose because of the lack of specific signs and symptoms.' Patients with pelvic arteriovenous malformation are at risk for massive bleeding when undergoing transrectal biopsies or transurethral resection of the prostate.(1,2) We report a case in which pelvic arteriovenous malformation was diagnosed on transrectal ultrasound during prostatic biopsy. Transrectal ultrasound demonstrated a tubular and tortuous hypoechoic lesion adjacent to the prostate, which was subsequently identified as a pelvic arteriovenous malformation on computerized tomography (CT) and arteriography. To our knowledge there have been no reports of transrectal ultrasound images of pelvic arteriovenous malformations.