The effectiveness of Lipiodol (iodized oil) in transcatheter arterial embolization (TAE) of hepatocellular carcinoma (HCC) was retrospectively evaluated using statistical analysis. A total of 343 HCC patients who underwent TAE at 5 institutions between 1984 and 1989 were divided into 2 groups: the GS-TAE group underwent TAE with Gelfoam sponge alone, whereas the LP-TAE group was given Lipiodol (LP) immediately before GS-TAE. The statistical T value calculated for the LP-TAE group showed that the administration of LP, the tumor size, intrahepatic metastasis, portal vein infiltration, and serum total bilirubin and alpha-fetoprotein levels significantly (P < 0.01) affected the patients' survival. Both the cumulative survival determined using the Kaplan-Meier model and the cumulative hazard calculated using Cox's proportional hazard model differed significantly (P < 0.01) between the GS-TAE group and the LP-TAE group (log-rank test). These results confirmed the effectiveness of LP used in combination with Gelfoam sponge for TAE of HCC.