The purpose of this study was to assess the clinical effects of transcatheter arterial chemoembolization (TACE) during the corresponding portal vein occlusion (TACE-PVO) in patients with hepatocellular carcinoma (HCC) and marked arterioportal (AP) shunts. This was a prospective, nonrandomized study of TACE-PVO in patients with HCC who had marked AP shunts. The subjects were 21 patients with unresectable HCC and marked AP shunts who underwent shunt embolization with the use of coils and/or gelatin-sponge particles (group A: n = 7) or by TACE-PVO (group B: n = 14). Clinical parameters and data on embolization of AP shunts and on tumor response were assessed prospectively. No major procedure-related complication occurred in either group. Effectiveness of AP-shunt treatment was significantly better in group B than in group A in terms of both immediate results (P = 0.009) and subsequent results (P = 0.028). Tumor response in the therapeutic target area was significantly (P = 0.002) better in group B than in group A. Survival was significantly better in group B than in group A (P = 0.008). TACE-PVO may be a safe and useful therapy for selected patients with unresectable HCC and marked AP shunts.