During the period from January 1981 to December 1983, two groups of a total of 51 patients (31 malignant astrocytomas, 17 glioblastomas, and 3 others) were treated with radioimmunochemotherapy using nimustine hydrochloride (ACNU) plus Picibanil (OK-432) (group A) and radiochemotherapy with ACNU only (group B) in a randomized controlled study. Group A consisted of 24 patients and group B of 27 patients. The differences in the background of the two groups were not statistically significant. Survival curves of both groups were shown by the Kaplan-Meier method. The postoperative survival rate at 1 year and 3 years was 70% and 30%, respectively, equal in both groups, and the differences between groups A and B were not statistically significant by the Cox-Mantel test. The side effects seen in group B were most prominent in the bone marrow, and severe leukopenia occurred. However, in group A leukopenia was suppressed after 2 months. Immunologic parameters, such as the purified protein derivative skin reaction test, did not change, but the streptococcus pyogenes Su-strain polysaccharide skin-reaction test became more positive after therapy in group A.