Nine patients with t(11;14) and B non-Hodgkin's lymphomas composed of small to intermediately sized cells with irregular nuclei are described. Immunophenotyping was performed on seven cases, which were M+, D- with light chain restriction, CD5+, CD10-, and CD20+, suggesting that they were non-follicle centre cell lymphomas. The translocation (11;14) (in three cases the only cytogenetic anomaly) was associated with rearrangement of bcl-1 in four of the five cases investigated. Translocation (11;14) has been described in an apparently heterogeneous group of low-grade lymphoid malignancies which we suggest have a non-follicle centre cell lineage in common. This translocation may be associated with these lymphomas in the same way that t(14;18) is associated with follicle centre cell lymphomas.