Intrahepatic distribution of the inferior mesenteric blood flow was evaluated with scintigraphy with transrectally administered 123I-iodoamphetamine (IMP). Twelve patients without liver diseases were studied. The IMP image was divided into 3 types; bilateral, left lobar predominant and right lobar predominant. Bilateral, left lobar predominant and right lobar predominant types were observed in 5, 5 and 2 patients respectively. Furthermore, uneven distribution pattern in the left or right lobe was observed in 2 of 5 patients with bilateral lobar type, 4 of 5 patients with left lobar predominant type and 1 of 2 patients with right lobar predominant type. In one patient with left lobar predominant type, repeat examination demonstrated bilateral lobar type. These results suggest that intrahepatic distribution of the inferior mesenteric blood flow is not uniform and consistent.