To characterize circulating gammadelta T cell subpopulations in B chronic lymphocytic leukaemia patients (n=30), TCR Vgamma and Vdelta gene-segment use was analyzed by RT-PCR using a panel of subfamily-specific oligonucleotide primers. All results were compared with those obtained with specimens from healthy donors (n=10). The cells expressing Vdelta1+ TCR displayed the highest relative increase in B-CLL patients (particularly observed in 60% of cases), but Vdelta3+ T lymphocytes also expanded in leukaemic peripheral blood (10% of studied cases). Both mentioned gammadelta T cell subsets were significantly more frequent in the most severe stages of disease--Rai III+IV. The analysis of Vgamma region usage in TCR formation revealed that gammadelta T cells from B-CLL patients predominantly expressed a Vgamma9 segment (26 of 30 cases), usually linked to Cgamma1 region. It should be noticed that the dominant TCR genes expression in a 50% of healthy donors was Vdelta2+/Vgamma9+, however, Vgamma4 and Vgamma8 transcripts were also observed (2 and 3 of 10 cases, respectively). The above results indirectly indicate that gammadelta T lymphocyte expansion was driven by the oligo- or polyclonal proliferation and can reflect specific response against the autologous tumor cells.