Panels of gamma delta T cell clones bearing the V gamma 9/V delta 2 form of TCR were derived from human first trimester decidualized endometrium and cervix. Seventy-three percent of these clones expressed the human mucosal lymphocyte Ag HML-1 compared with only 14% of PBL V gamma 9/V delta 2 clones, indicating that most clones were derived from the tissue itself rather than contaminating peripheral blood. All 13 clones isolated expressed V gamma 9JPC gamma 1- and V delta 2(D)J delta 1-encoded receptors; TCR gamma and delta junctional regions from most of these were sequenced and analyzed, together with the TCR-delta junctional region of a sequence obtained from bulk CD3+ decidual leukocytes. There was considerable junctional diversity of both gamma- and delta-chains with a similar extent of germline V and J gene trimming and N-region nucleotide addition to that found in PBL V gamma 9/V delta 2 cells. Eight of eleven TCR-delta junctional sequences contained a strongly hydrophobic amino acid in position 97, as has been found in > 90% o V gamma 9/V delta 2 clones. Thymic V gamma 9/V delta 2 cells show much less junctional diversity and less pronounced selection at residue 97 of the delta-chain. Thus, unlike the mouse, gamma delta T cells from human female reproductive tissues exhibit extensive TCR junctional as well as combinatorial diversity. This suggests that V gamma 9/V delta 2 cells in these human tissues have undergone selective but diverse peripheral expansion in response to antigenic stimuli in a similar manner to those in peripheral blood.