PURPOSE: To evaluate the use of percutaneous microwave coagulation therapy for hepatocellular carcinoma, particularly with tumor nodules larger than 2cm in diameter. MATERIALS AND METHODS: Fifty patients with 107 hepatocellular carcinoma nodules (mean diameter, 2.7cm 6 1.5 [SD]; range, 0.8-6.4 cm) were treated with percutaneous microwave coagulation therapy. Single electrode insertion was used in 46 nodules (43.0%) 2cm or smaller, whereas multiple electrode insertion was applied in 61 (57.0%) nodules larger than 2cm. RESULTS: At 1 month after therapy, technical success for tumors 2cm or smaller and those larger than 2cm was achieved in 45 (98%) and 56 (92%) nodules, respectively. After follow-up of 9 months or longer, local recurrence was found in one nodule (2%) sized 1.8cm and in five nodules (8%) larger than 2cm. At the end of the study, 26 (52%) of 50 patients were free of disease, and disease-free survival rates at 1 and 2 years were 55% and 41%, respectively. Overall survival rates at 1, 2, and 3 years were 96%, 83%, and 73%, respectively. CONCLUSION: Percutaneous microwave coagulation therapy is an effective and safe therapeutic modality for hepatocellular carcinoma. A multiple electrode insertion technique can enhance the effectiveness of this therapy in tumors 6cm or smaller.