Of 187 specimens of non-Hodgkin's lymphoma and four hyperplastic lymphoid proliferations with clonal chromosome abnormalities ascertained serially over a 4 1/2-year period, nine cases with t(3;22)(q27;q11) were identified. Seven of the lymphomas were diffuse tumors, predominantly large cell type. The eighth tumor, a follicular small cleaved cell lymphoma, exhibited a t(3;22) and a t(14;18)(q32;q21). The ninth case was a lymph node from a human immunodeficiency virus-positive patient which showed atypical hyperplasia. Overall survival of t(3;22) diffuse lymphoma patients was not different from that of patients with abnormal karyotypes without t(3;22). The t(3;22) diffuse tumors studied showed a disproportionate frequency of lambda light chain on their cell surfaces, a finding similar to that observed in t(8;22)(q24;q11) Burkitt's lymphomas. Our results indicate that the t(3;22)(q27;q11) is the third most common recurring translocation in diffuse non-Hodgkin's lymphoma.