In an attempt to ascertain the possible beneficial or adverse effects of ethanol injection into a hepatic malignant tumor, we carried out a series of experiments using the RBT-1 carcinoma. Ten days after the inoculation of RBT-1 carcinoma into the rat livers, the animals were separated into four groups: group A received a sham operation, group B had ethanol injections directly into the hepatic tumor, group C underwent tumor removal and group D underwent tumor removal 20 min after ethanol injection. When a comparison was made with all groups, survival time was significantly longer in group B than in A (p < 0.01), group C than A (p < 0.01) and group C than B (p < 0.01). The incidence of vascular permeation of liver tumor cells into the hepatic vein was significantly higher in group D than C (p < 0.05). Twenty days after initial injection of RBT-1 tumor, 10 rats in each group were killed, and their lungs were assessed for evidence of metastatic spread of tumor. The number of metastatic nodules in the lungs was significantly increased in those rats that had undergone intrahepatic ethanol injection vs. those that had not (group B vs. A [p < 0.05] and group D vs. C [p < 0.05]). The number of metastatic nodules in the lungs differed significantly in those rats that had undergone hepatectomy vs. those that had not. These results are taken to mean that hepatectomy and ethanol injection into a tumor was an effective therapy.(ABSTRACT TRUNCATED AT 250 WORDS)