In order to study the role of gamma/delta T cells in the pathogenesis of inflammatory bowel disease (IBD) in humans, we measured the percentage of these cells in the peripheral blood, assessed the ratio of the non-disulphide-linked (delta TCS1) type of T cell receptor (TCR) in the total gamma/delta T cells, studied the co-expression of gamma/delta TCR and accessory molecules CD8 and CD16, and compared these data with both the type and the activity of the disease.