A 60-year-old man with multiple hepatocellular carcinomas (HCCs) was enrolled as the first patient in a pilot study for treating multiple liver tumors with boron neutron capture therapy (BNCT). Because of compromised liver function, the multiple tumors in the right liver lobe were treated with BNCT and those in the left lobe with hepatic arterial chemoembolization. The feasibility and clinical outcome of this first case was assessed. During the treatment and follow-up period, no adverse effect as a result of BNCT was observed except for temporary temperature elevation to 38.3 degrees C, and the AST and ALT being higher than 200 IU/l. For 1 month, the tumors treated with BNCT remained stable in size. The BNCT-treated tumors showed regrowth 3.5 months after BNCT and the patient died of liver dysfunction caused by progression of HCC 10 months after BNCT. The feasibility of BNCT for HCC is confirmed in this first case.