Two groups of patients suffered from ovarian carcinoma were studied retrospectively after similar treatments; in one group of 22 patients radioimmunoimaging (RII) had been used, which was not used in the other group of 15 patients. Other factors were similar in the two group such as hospitalization period, courses of surgical treatment and regimes of chemotherapy after surgery. The staging according to FIGO was also similar in the two groups except that the number of patients in stage III was 14 in the RII group but 8 in the non-RII group. Neither the age distribution nor the histopathological diagnosis was of much difference. 131I labeled monoclonal antibody against ovarian serous adenocarcinoma, generated in our laboratory, was given to all patients intraperitoneally either before or after the surgery; 7 cases before the initial operation, 9 cases before the second look operation and 6 cases for follow up after surgery and chemotherapy. The death rates of stage III were 42.9% and 75.0% in the RII group and non-RII group respectively. By means of Kaplain Meir's life table calculation the 3 year survival rates for the two groups were 63.5% and 25.0% respectively. The RII group was obviously higher than the non-RII group even though not statistically significant. These results were similar to those reported in the literature. Three very late cases of ovarian carcinoma were reported, in whom RII had been used, are still living after follow-up for more than 5 years. The beneficial role of induction of the idiotypic network was discussed, and the possibility of innoculation is under investigation.