The effects of immunotherapy with IL-2 were evaluated in 10 patients with advanced cancers for whom standard anticancer chemotherapy had been ineffective from Apr. 1988 to Mar. 1989. Of total 10 patients, five were treated witn 24 hr continuous IV infusion of IL-2 with the dosage of 1 x 10(4) u/kg/day or 1 x 10(5) u/kg/day respectively for 5 days and another five with intraperitoneal bolus infusion of IL-2 with the dosage of 1 x10(4) u/kg/day or 1 x 10(5) u/kg/day after removal of ascites by paracenthesis for 5 days. Of the 10 evaluable patients, 9 (90%) patients had no response and only 1 (10%) had minimal response. One patient who had minmal response had squamous cell ca of esophagus and has received IL-2 intravenously. Most common side effects were fever and chills and they could be prevented or alleviated by use of NSAIDs or IV infusion of Meperidine in severe cases. Serious side effects were capillay leak syndrome and its complication which show hypotension, generalized edema, weight gaine and azotemia. GI symptom, rigor and skin lesion were also obseved. But pulmonary edema was not observed. All of the above side effects were well overcome by conservative management. In the intraperitoneal infusion group the side effects occurred less frequently than IV infusion group. Anemia, neutropenia, eosinophilia, azotemia and abnormal liver function test were observed, but they have returned to normal range after discontinuation of IL-2 infusion. The absolute lymphocyte counts decreased I day after IV infusion of IL-2 and came back to show revound lymphocytosis from the next day after discontinuation of IL-2 infusion. They returned to pretreatment level from the 4th day of discontinuation of IL-2 infusion. In the intraperitoneal infusion group total WBC counts in ascites began to increase from 24 hrs after IL-2 infusion and reached peak at the end day of infusion. They began to decreased with discontinuation of infusion. Compared with WBC counts in ascites, those in peripheral blood showed delayed increase. In conclusion, 1 x 10' and 1 x 10 u/kg/day infusion of IL-2 were enough to increase the lymphocyte pool in vivo respectively, although no effective clinical response was obtained. There was no difference in the clinical and side effects between 1 x 10(4) and 1 x 10(5) u/kg/day infusion groups. This study warrants for further investigation into the determination of effeective therapeutic concentration of IL-2 and its route of adminstration.