The present study reports on the usefulness of laparoscopic microwave coagulonecrotic therapy as a new option in the treatment of hepatocellular carcinoma. Five patients with liver tumors associated with cirrhosis were treated from July 1993 to March 1994 with a microwave electrode (output 100 W, 3 to 4 cm long) devised for laparoscopic use. The tumors, all with diameters less than 3 cm and superficially located, were coagulated for a total radiation period of 20 to 30 min under laparoscopic, intraoperative ultrasonographic control. Postoperative complications were negligible, and laboratory values (glutamate-pyruvate transaminase, bilirubin, prothrombin time, platelet count) returned to preoperative levels within 7 days. Complete necrosis, including the surrounding liver tissue, was confirmed by a follow-up dynamic computed tomography scan during the follow-up period of 6 to 17 months (mean, 13 months). Laparoscopic microwave coagulonecrotic therapy can exert an effect on tumor equivalent to that obtained from a wedge resection but is noninvasive and may represent a new option for unresectable liver cancers.