Increased numbers of T cells bearing the gamma delta antigen receptor (gamma delta T cells) have been reported in small bowel biopsies of patients with latent, active or treated coeliac disease. We have studied jejunal biopsies from seven children with coeliac disease and 10 children with normal gut histology to characterize gamma delta T cell receptor (TCR) variable region gene subfamily expression in resident gamma delta T cells and compared the results with the findings in peripheral blood mononuclear cells (PBMC) obtained on the same day as the gut biopsy. Molecular analysis of RNA extracted from PBMC and biopsies was performed by reverse transcription and amplification with the polymerase chain reaction using primers specific for six TCR V delta families and four TCR V gamma families. We report, first, that a significantly increased number of gamma delta T cells expressing the TCR V delta 3 subfamily (P = 0.008) was observed in jejunal biopsies from children with coeliac disease, and second, that gamma delta T cell V region subfamily populations in gut differed from those seen in PBMC for both control and coeliac patients. Significantly reduced numbers of TCR V delta 2, V delta 3, V delta 5 (P < 0.01) and V gamma 2, V gamma 4 (P < 0.01) T cells were found in gut compared with PBMC. The difference in gamma delta T cell repertoire observed between gut and blood may reflect differences in the nature of the antigens usually encountered in these two compartments. The over-representation of TCR V delta 3 in patients with coeliac disease suggests a specific role for these cells in the induction or maintenance of the jejunal abnormality associated with this disease.