Ten patients with testicular relapse among 128 cases of acute lymphoblastic leukemia are reported. At the time of the initial diagnosis of leukemia all patients with later testicular relapse showed one or more risk factors as predictive for leukemic infiltration of the testicles. All patients except one, who underwent orchiectomy and died 11 weeks after surgical intervention, received radiation therapy with doses ranging from 12 to 20 Gy and chemotherapy. The local control was excellent. Average survival time from testicular relapse to death was 68 weeks in 8 of 9 patients treated by irradiation and chemotherapy. One patient is still alive without signs of disease after 6 years.