A prognostic study on 119 patients with primary liver cancer undergoing nonsurgical therapy was carried out to evaluate the relevance of hepatic functional reserve and tumor size to their cumulative survival rates. All patients were classified into the three groups of Child's classification (A, B and C) according to their hepatic functional reserve and were also divided into the five groups according to their tumor size. The cumulative survival rates of all patients at 1, 2, 3, 4 and 5 years after the diagnosis were 50.9, 28.3, 18.8, 13.5 and 6.7%, respectively. The cumulative survival rates of group V whose tumor occupied more than 40% of the liver area were significantly lower than those of the other tumor-size-groups. The survival rates of Child's group A were significantly higher than those of group B and C. But in those patients who were classified into group V according to their tumor size, there was no significant difference in their survival rates among the three groups of Child's classification. These results suggest that hepatic functional reserve as well as tumor size is an important prognostic factor in patients with primary liver cancer. But if the cancer once develops greater than 40% of the liver area, hepatic functional reserve diminishes in value as a prognostic factor.