From November 1973 to June 1992, cryosurgery with liquid nitrogen (-196 degrees C) was performed on 113 patients with hepatic cancer, including 107 patients with primary liver cancer (PLC) and 6 patients with secondary liver cancer (SLC). Of the 107 PLC patients, the subclinical stage constituted 30.8% (33/107), the moderate stage 61.7% (66/107), and the late stage 7.5% (8/107). There were 32 cases with small PLC (up to 5 cm). Liver cirrhosis was observed in 86.0% (92/107). We designed flat cryoprobes for freezing tumors deep within the hepatic parenchyma. Intraoperative ultrasound was used for monitoring hepatic cryolesions. There were no operative mortalities and complications, such as rupture of a tumor, delayed bleeding, or bile leakage. The 5-year and 10-year survival rates were 22.0% and 8.2%, respectively, for the 107 PLC patients and 48.8% and 17.1%, respectively, for the 32 patients with small PLC. Of the 6 SLC patients, survival ranged from 2 months to 90 months (average, 23.2 months). One SLC patient has been well for 7 years and 6 months after cryosurgery. These results indicate that cryosurgery, the in situ freezing of cancer, is a safe and effective treatment for unresectable hepatic cancer.