Histological and immunohistological studies were made in 28 patients with testicular lymphoma who presented with a right (15), left (11) or bilateral (2) scrotal swelling. Patient age at hospitalization ranged from 39 to 87 years, with a median age of 64 years. The disease was stage 1 in 12 patients, stage 2 in 11 and stage 3 in 5. Histologically, most of the neoplasms were of the diffuse large cell type, with an immunoblastic type being the most common. Immunohistochemistry revealed that all but 2 cases were of the B cell type. None of the tumors reacted with monoclonal antibody for T cell. These findings suggested that testicular lymphoma exclusively consisted of the B cell type, identical to previous reports of extranodal lymphomas other than those in the skin. The pertinent literature is reviewed and the histogenesis of testicular lymphoma is discussed.