Malignant lymphomas (ML) with t(3;14) or variant t(2;3) and t(3;22) have recently been recognized. These translocations have been shown to associate predominantly with B-cell diffuse large cell lymphoma (DLCL) and less frequently with follicular lymphoma (FL). The molecular alterations associated with these translocations involve one of the immunoglobulin gene (Ig) loci and a recently cloned gene, bcl-6 located at 3q27 which codes for a zinc-finger protein that may function as a transcription factor. We have identified by cytogenetic analysis 22 cases of ML with a 3q27/Ig translocation. The pathologic diagnoses of these cases include DLCL, FL, small non-cleaved non-Burkitt lymphoma and chronic lymphocytic leukaemia. Molecular analysis confirmed a bcl-6 rearrangement in 10/12 cases tested. The karyotype in 5/22 cases revealed the t(3;14) or variant in association with another lymphoma-specific translocation, t(14;18) in three cases and t(8;14) in two cases. ML with dual translocations that implicate Ig genes in the deregulation of proto-oncogenes are being increasingly recognized and may represent distinct subtypes or 'hybrid' forms of malignant lymphoma.