Structural chromosomal abnormalities and their break-points were characterized in 17 patients with multiple myeloma (MM) and 4 with plasma cell leukemia by banding. Chromosome 14q32 translocations with a variety of partners were detected in 13 patients, and a variant translocation t(8;22)(q24.1;q11) was detected in 1. Three recurrent 14q32 translocations have been identified: t(6;14)(p21.1;q32.3) occurring in 3 cases, and t(11;14)(q13;q32.3) and t(14;18) (q32.3;q21.3) each occurring in 2 cases. Translocations t(1;14)(q21;q32.3), t(3;14)(p11;q32),t(7;14)(q11.2;q32.3), and t(11;14)(q23;q32.3) were found in each patient, whereas in the remaining 2 patients, partner chromosomes could not be determined. The band 19p13.3 was newly delineated as a recurrent breakpoint involved in translocations in MM. Chromosomes 1 and 6 were also commonly involved in structural abnormalities (14 and 10 patients, respectively), although no particular bands were noted. However, the short arm of chromosome 1 was preferentially involved in deletion, suggesting a certain antioncogene on 1p associated with the development of myeloma. In addition; fluorescence in situ hybridization was successfully applied to determine the nature of the structural abnormalities in a patient with t(8;22) translocation. The present findings suggest that there may be subsets of 14q32 translocations specific to MM.