Objectives: Lymphoma is the most frequent testicular malignancy in men over 60 years of age. Even though patients present initially with localized disease, the high incidence of bilateral involvement, synchronous or not, and early systemic dissemination are characteristic of these neoplasms. Sometimes the interval between tumor involvement of both testes is long. the question is raised whether either the patient has a predisposition to present new clones of transformed lymphocytes, or the same disease using the same pathway from a systemic reservoir infiltrates the contralateral testis.Method: Polymerase chain reaction and DNA sequencing were used to detect immunoglobulin heavy chain (IgH) rearrangement in paraffin-embedded specimens from asynchronous tumors affecting the right and left testis of a 85-year-old man with an interval period of 13 months.Results: Both tumors showed the same IgH rearrangement.Conclusions.. the lymphoma affecting the left and right testis derived from the same clone. It makes a strong case that lymphoma of the testis is the first manifestation of a systemic disease and should be treated aggressively early at the beginning of the disease. Copyright (C) 2000 S. Karger AG. Basel.Sirio Libanes Hosp, Lab Mol & Surg Pathol, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Div Urol, São Paulo, BrazilHosp A C Camargo, Lab Pathol Clin & Hemoterapia, São Paulo, BrazilUniversidade Federal de São Paulo, Escola Paulista Med, Div Urol, São Paulo, BrazilWeb of Scienc