We have analyzed the chromosomes of 49 non-Hodgkin lymphoma patients from an area of Japan that is nonendemic for adult T-cell leukemia/lymphoma. Clonal chromosome abnormalities were found in the majority (88%) of the specimens examined. The most characteristic structural abnormalities were: t(14;18)(q32;q21), t(3;22)(q27;q11), t(11;14)(q13;32), idic(18)(p11.2), and the combination del(1)(p13) and del(1)(q11). The t(14;18) were found in four of five follicular lymphomas and in one diffuse lymphoma. The breaks at 3q27 included seven translocations and an inv(3)(q12q27). A t(3;22) was found in three patients, all B-cell type, two of whom had kappa phenotype and one of whom was negative for the surface Ig. Fifteen of 49 cases had deletion of 6q. The common deleted region was found only in the segment distal to 6q21. These findings indicate the high percentage of t(14;18) in follicular lymphomas, which is unusual in Japan, and the high incidence of 3q27 translocations.