The distribution of T lymphocytes expressing the gamma/delta form of the T cell receptor was studied in the liver, intestine, and major lymphoid organs, after bone marrow transplantation (BMT), including cases of graft versus host disease (GvHD). The number of gamma/delta as a proportion of the total number of CD3 positive cells did not differ from that found in normal tissues; the higher percentage normally found in the intestinal epithelium and splenic red pulp was maintained. This, and the results of a previous study undertaken on the skin, provide no evidence that gamma/delta T cells have a particularly important role in T cell regeneration after marrow transplantation or in the pathogenesis of the epithelial lesions associated with GvHD.