PURPOSE To evaluate a combination of thioguanine, procarbazine, dibromodulcitol, CCNU (CCNU), fluorouracil, and hydroxyurea (TPDC-FuHu), designed to improve the efficacy of CCNU, in the treatment of recurrent metastatic brain tumors. PATIENTS AND METHODS One hundred fifteen patients with progressive or recurrent metastatic brain tumors that failed to respond to surgery and/or radiation therapy were enrolled onto a multicenter prospective study between 1989 and 1995. Patients received TPDC-FuHu in a repeated cycle every 6 weeks until recurrence or until they completed six courses. RESULTS Ninety-seven patients were assessable at the end of the study. Forty-eight had lung cancer (39 non-small-cell [NSCLC] and nine small-cell [SCLC]), 28 had breast cancer, nine had melanoma, and 12 had adenocarcinoma of different origins (three colon, two kidney, one bladder, one stomach, and five of unknown origin). The response and stable disease (SD) rate (overall response rate) was 52%, 66%, 60%, and 22% in patients with NSCLC, SCLC, breast cancer, and melanoma, respectively. Median time to progression (MTP) was 12, 26, 12, and 6 weeks, respectively, for the four groups. Side effects were mild to moderate in the majority of patients. Severe myelosuppression (grade 4) occurred in only 11% of the patients. CONCLUSION TPDC-FuHu chemotherapy is an active treatment against recurrent brain metastases from breast cancer and SCLC, and to a lesser extent from NSCLC. This regimen is well tolerated and has acceptable toxicity.