We studied T-cell receptor (TCR) repertoire of circulating gamma delta (gammadelta) T-cells in 20 patients with Takayasu's arteritis (TA), 20 healthy controls (HC), 7 follow up TA patients, and 10 patients with rheumatoid arthritis (RA) and 5 Wegener's granulomatosis (WG) patients as disease controls. Patients with TA (8.1 +/- 5.1%) compared to HC (3.7 +/- 2.1%, P = 0.014), RA (4.8 +/- 0.6%, P = 0.032), and WG (4.2 +/- 0.8%, P = 0.030) as well as active TA compared to inactive TA (13.9 +/- 4.1% vs. 4.9 +/- 1.5%; P < 0.001) had higher number of gammadelta T-cells. The numbers of Vdelta1+ cells were significantly higher in patients with TA (40.0 +/- 20.8%) than HC (13.1 +/- 8.0%; P = 0.001), RA (19.5 +/- 1.8%, P = 0.004), and WG (17.0 +/- 3.9%, P = 0.007). The numbers of gammadelta T-cells normalized in all the 7 patients after 180 days of follow up (13.9 +/- 4.1% vs. 6.9 +/- 2.5%; P = 0.001). We also observed higher number of activated and IFN-gamma producing gammadelta T-cells in active TA. Our data show that gammadelta T-cells particularly those bearing Vdelta1 TCR may have an important role in the immunopathogenesis of TA.