Hepatocellular carcinoma is a major malignant disease in parts of Africa and Asia, including Korea. Surgical resection, which represents the best hope for cure, is limited by the extent of the disease and the high incidence of concurrent liver cirrhosis in Korea. We designed a phase H trial of combined external radiotherapy and hyperthermia for hepatocellular carcinoma that was unresectable due to either locally advanced lesions or associated liver cirrhosis so as to evaluate the efficacy and the safety of this combination regimen. This trial was performed at Yonsei Cancer Center between April 1988 and July 1988. External radiotherapy was delivered to a total dose of 3060 cGy/3.5 weeks. Hyperthermia was applied twice a week for a total of six treatment sessions using an 8-MHz radiofrequency capacitive-type heating device, i. e., Thermotron RF-8 and Cancermia. In all cases, hyperthermia was carried out within 30 min of the radiotherapy for a period of 30–60 min. The temperature in the tumor was measured by inserting a thermocouple into the tumor mass under ultrasonographic guidance in patients who did not have a bleeding tendency. The tumor response was assessed by CT scan after completion of the designed treatment. No complete response was obtained. However, a symptomatic improvement in abdominal pain was observed in 78.6% of cases and a partial response was achieved in 40% of the patients. The most important factor affecting the tumor response was the type of tumor (single massive, 71.4%; diffuse infiltrative, 20%; multinodular, 0;P<0.005). the="" 1-year="" survival="" values="" determined="" for="" all="" patients="" and="" for="" the="" partial="" responders="" were="" 34%="" and="" 50%,="" respectively.="" the="" overall="" median="" duration="" of="" survival="" was="" 6.5="" months.="" the="" median="" duration="" of="" survival="" for="" the="" partial="" responders="" was="" longer="" than="" that="" for="" the="" nonresponders="" (11="" vs="" 5="">P<0.05). a="" mild="" degree="" of="" heat="" sensation,="" fever,="" first-degree="" burns="" of="" the="" skin,="" and="" nausea="" were="" observed="" as="" treatment-related="" adverse="" reactions.="" in="" conclusion,="" although="" this="" study="" is="" being="" continued,="" the="" results="" obtained="" thus="" for="" indicate="" that="" combined="" radiotherapy="" and="" hyperthermia="" seem="" to="" be="" effective="" in="" providing="" local="" tumor="" control="" and="" pain="" palliation="" in="" unresectable="" hepatocellular="" carcinoma="" while="" producing="" an="" acceptable="" level="" of="">