Using immunohistology and monoclonal antibodies directed to the T-cell receptor (TCR) chains, we have analysed the distribution of TCR-bearing lymphocytes within the membrane of rheumatoid arthritis (RA) patients. Alkaline phosphatase staining for TCR alpha beta-bearing lymphocytes showed a distribution paralleling that of the total T cells. Staining for the TCR gamma delta chains revealed a moderate and rather homogeneous distribution of T gamma delta lymphocytes within the RA synovium. As evidenced by simultaneous staining for alpha beta and gamma delta receptors, the relative count of T gamma delta to alpha beta-expressing cells is close to the peripheral count (e.g.5%), and lower than that previously observed in the synovial fluid. Interestingly, the peripheral type V gamma 9-J gamma P rearrangement using the T gamma delta cell subset was relatively decreased in the synovial membrane, as compared to synovial fluid and peripheral blood, suggesting that the T gamma delta distribution in the rheumatoid synovium resembles a thymic-like situation.