The present report is the follow-up of patients enrolled in a phase II clinical trial using 125I-MAb 425 as an adjuvant treatment for high grade gliomas. Patient median survivals support published data from an earlier preliminary report. From January 29, 1987 to January 25, 1997, 180 patients diagnosed with astrocytoma with anaplastic foci (AAF) and glioblastoma multiforme (GBM) were treated as outpatients with an average of three weekly intravenous or intraarterial injections of radiolabeled MAb 425. The mean dose was 140 mCi (5.2 GBq). Only one patient who received a single dose of more than 60 mCi (2.2 GBq) experienced acute toxicity. Patients received prior surgery and radiation therapy, with and without chemotherapy. Overall median survival for patients with GBM and AAF was 13.4 and 50.9 months, respectively, with Karnofsky Performance Status (KPS) ranging from 40 to 100 and age ranging from 11 to 75 years. Prognostic factors (KPS and age) correlated positively with increased survival, with KPS the most important determinant of median survival. Data analysis was performed on patients followed 5 years or longer. We conclude that the administration of 125I-MAb 425 with intensive medical management demonstrates a significant increase in median survival and should be considered a therapeutic regimen for the management of patients with high grade gliomas.