We have determined the distribution of T gamma delta cells in the peripheral blood of 44 patients with rheumatoid arthritis and in 36 healthy controls. In addition, paired blood and synovial fluid samples were obtained from seven patients with RA. The monoclonal antibodies A13, BB3 and Ti gamma A, which are specific for the V delta 1, V delta 2 and V gamma 9 gene products respectively, were used to define T gamma delta subsets. T gamma delta + cells expressed as a percentage of CD3+ lymphocytes were reduced in RA peripheral blood compared with the control group (3.9% +/- 0.5 versus 5.7% +/- 0.7; P less than 0.0001). There was a reduction in the V gamma 9/V delta 2+ subset (from 5.6% +/- 1.2 to 1.7% +/- 0.4) leading to a change in the mean ratio of V delta 2/V delta 1+ cells from 4.3 in normal subjects to 1.1 (P less than 0.002). No statistical difference was observed in T gamma delta cell numbers in synovial fluid compared with the paired blood samples (4.0% +/- 1.1 in blood and 4.4% +/- 1.4 in synovial fluid). Also the distribution of V delta 2+ and V delta 1+ cells was similar in the two compartments and a similar alteration in subset distribution was found in blood and synovial fluid. These findings do not indicate a selective accumulation of a specific T gamma delta subset in RA synovial effusions.