TCR gene rearrangement detection has proven to be a useful diagnostic method. In this work, 88 T-cell lymphoproliferative disorders and 45 non-T-cell proliferation in Japanese patients were studied for rearrangement of TCRG and TCRB using PCR and multiplex PCR. The sensitivity and specificity of TCRB assay in mature T-cell proliferation were 98.2% and 90.9%, respectively. The sensitivity and specificity of TCRG were 84.0% and 73.3%, respectively. The combination of rearranged TCRG and TCRB analysis provides an extremely high sensitivity for the diagnosis of mature T-cell proliferative disorders. All patients in this group exhibited rearrangement of either TCRG or TCRB or both TCRG and TCRB. All cases of Blymphoid malignancies and reactive lymphoid cases tested for TCRB-DJ gave complete negative results, thus providing an alternative discrimination from CD3(+) and T-cell leukemia/lymphoma. Although 25% of B-cell non-Hodgkin lymphoma (BNHL) cases revealed TCRG rearrangement, all B-NHL cases gave negative TCRB rearrangement. In summary, PCR-based combination analysis of TCRG and TCRB rearrangement is a powerful diagnostic tool which also provides accurate discrimination for each type of lymphoproliferative disorder.