Centrocytic lymphoma is a B-cell non-Hodgkin's lymphoma (NHL) composed of lymphocytes resembling cleaved follicular center cells (centrocytes). Previous studies have suggested an association between t(11;14) chromosomal translocations and bcl-1 rearrangement in centrocytic and related intermediate lymphocytic lymphomas. To further characterize the association between bcl-1 and centrocytic lymphoma, Southern blot analysis was performed on samples from 23 patients using four separate bcl-1 breakpoint probes spanning 63 kb of the chromosome 11 bcl-1 locus. Rearrangements were identified in six patients with the major translocation cluster (MTC) probe and in another six with probe p94PS, located about 24 kb 5' of MTC. Eleven of these 12 cases showed comigration of rearranged bcl-1 and Ig heavy chain-joining genes, consistent with the t(11;14) chromosomal translocation. No rearrangements were observed with the bcl-1 locus probes p210 or p11EH located 5' of p94PS, nor with bcl-2 or c-myc oncogene probes. No bcl-1 rearrangements were identified in B-cell follicular NHL (15), small noncleaved cell (Burkitt's and non-Burkitt's) NHL (8), T-cell NHL (4), multiple myeloma (14), and pre-B-cell acute lymphoblastic leukemia (9). One of 23 B-cell NHL of large cell type and one of 19 chronic lymphocytic leukemias or small lymphocytic NHL had MTC rearrangement. Thus, bcl-1 rearrangement occurred at MTC or p94PS in 12 of 23 centrocytic lymphomas (52%), confirming a nonrandom association and suggesting a pathogenetic role for the bcl-1 locus in this immunohistologic subtype of NHL.