Twelve consecutive cases of non-Hodgkin's lymphomas with initial testicular involvement have been considered in this retrospective evaluation. In 801 cases with referred for treatment to the Istituto Nazionale Tumori of Milan from 1962 to 1974 evidence of initial testicular involvement was observed in 1,4% of cases. Of the whole group of testicular tumors treated in our Institute only 3% were classified as non-Hodgkin's lymphomas. Six out of 12 patients with stage I (2 cases) and II (4 cases) diseases were treated with Cobalt therapy to the retroperitoneal nodes. Only one patient remained free of disease after radiotherapy. Three patients relapsed after primary irradiation and six patients classified as stage IV were treated with chemotherapy. Patients receiving combination chemotherapy had in general a better quality of response and a larger, but not significantly different, survival, compared to patients given simple agent sequential chemotherapy. Since the differential diagnosis between testicular lymphomas and seminomas may cause some difficulties and therapeutic implications are different, clinicians should be alert to this problem: in our case series testicular non-Hodgkin's lymphomas was the most frequent non-germinal tumor of the testicle.