Because of its rarity, there is a paucity of information in the medical literature about testicular lymphoma in young people. In our series of 99 patients with non-Hodgkin's lymphoma, 12% percent of the male patients had one or both testes involved at the time of diagnosis. Of the nine patients with testicular disease, six had Burkitt's, one undifferentiated non-Burkitt's, one diffuse large cell, and one lymphoblastic lymphoma. The mean age was 17.8 years (range, 2-30 years). Seven patients had unilateral and two had bilateral clinical testicular involvement, and all nine had extensive disease with abdominal involvement. Gallium scan indicated occult disease in the contralateral testis in two patients, bringing the total number with bilateral disease to four. In the patients with nonlymphoblastic lymphoma, the mean duration of survival was 68.3 months for three patients with long-term remissions and 4.4 months for five patients who died. The poor survival probably reflects extensive disease rather than testicular involvement per se. One patient relapsed in the testis, but achieved long-term survival after orchiectomy, scrotal irradiation, and continuation of the same systemic chemotherapy, suggesting that the testis may be a sanctuary site. Local therapy is considered to be an important component of treatment.