Boys with acute lymphoblastic leukemia (ALL) who have overt testicular relapse (OTR) during initial continuation chemotherapy or within 6 months thereafter have poor outcomes, with long-term survival similar to patients with marrow relapse during treatment. In April 1983, the Pediatric Oncology Group (POG) adopted for these patients an intensive treatment protocol (POG 8303) consisting of a four-drug systemic reinduction (prednisone, vincristine, daunorubicin, and asparaginase), a brief intensive consolidation phase with teniposide and cytarabine, and a 2-year program of continuation chemotherapy with weekly rotating drug pairs (vincristine/cyclophosphamide and teniposide/cytarabine) with or without (by randomization) four-drug reinforcement pulses every 16 weeks. Bilateral testicular radiation (2600 cGy) was administered during reinduction, and intrathecal chemoprophylaxis was given every 4 to 6 weeks. Among 38 eligible study patients with OTR, 5 had prior or concominant extramedullary relapse in other sites. The median duration of complete remission before OTR was 27 months (range, 10 to 42 months). All 38 patients achieved clinical remission after reinduction. Three patients withdrew while in remission, 22 had another relapse (12 marrow, 5 central nervous system (CNS), 2 testicular, 1 retroperitoneal, 1 prostate, and 1 eye), and 13 (34%) remain in complete remission from 32+ to 74+ months after OTR (median, 53+ months). Eighteen patients had their therapy electively discontinued, and five relapses occurred thereafter. These results are superior to those observed in patients with first marrow relapse treated with the same protocol. Approximately one third of patients with OTR treated with POG protocol 8303 exhibit prolonged second remissions with the potential for cure.