The distribution of T-lymphocytes expressing CD3 and T-cell receptor gamma-delta (T gamma/delta) has been examined by immunocytochemistry in the synovial membrane of eight patients with inflammatory arthritis (six rheumatoid arthritis, two spondyloarthritis) and eight with non-inflammatory arthritis (four osteoarthritis, four post-traumatic arthritis). T gamma/delta cells were present in eight out of eight inflammatory arthritis synovial membranes, but in only one out of eight non-inflammatory membranes (P less than 0.005). The mean T gamma/delta percentage (of total T-cells) in inflammatory arthritis was 14% (range 7-25%). T gamma/delta cells were found mainly in the transitional area of the synovial membrane with a scattered distribution as single cells or couplets. No relation was found between the presence and percentage of T gamma/delta cells and disease duration or steroid treatment.