Systemic sclerosis (SSc) is a multisystem disease characterized by T-cell infiltration of involved tissues, fibrosis, and small vessel vasculopathy. Using flow cytometric analyses, we found an increased percentage of gamma/delta T-cells expressing the T-cell antigen receptor variable (V) delta 1 gene segment in the peripheral blood and bronchoalveolar lavage fluid of patients with SSc. To estimate clonality of these V delta 1+ T-cells, the diversity of V delta 1 junctional regions (V-Diversity-Joining gene segments) was examined using a reverse transcriptase-polymerase chain reaction to amplify T-cell antigen receptor delta chain transcripts isolated from peripheral blood mononuclear cells, lung, esophagus, stomach, or skin of patients and controls. Limited diversity of V delta 1-J delta junctional regions in SSc patients was demonstrated by the finding of greater restriction in the nucleotide lengths of junctional region cDNAs in individual SSc patients than in controls. Sequence analyses confirmed that V delta 1-J delta junctional regions from the blood of SSc patients had less diversity than those from controls, in that a significantly higher proportion of sequences were repeated in patients (54.4% vs. 19.4% in controls). Evidence for selection of the V delta 1+ T-cells in tissues of individual SSc patients came from the findings that the same V delta 1-J delta junctional sequences could be isolated from the same tissue over time and that identical V delta 1-J delta junctional sequences could be isolated from multiple tissues. These data suggest that expansion of V delta 1+ gamma/delta T cells may be antigen driven in SSc patients.