The unique cellular composition of lymph has long been of interest to investigators studying immunological phenomena. The lymphocyte is the major cell present in lymph. Previous efforts to assess the effect of lymphocyte depletion via a thoracic duct lymph fistula have been impeded by numerous technical difficulties in maintaining the fistula.1-7 Short-term lymph fistulas in experimental animals and man have generally resulted in some prolongation of cellular allograft survival.1-7 Similar evidence of prolonged renal allograft survival in humans has been reported, but it is difficult to assess the effect of the depletion of lymphocytes because of the concurrent use of immunosuppressive agents.8,9 Recent reports of marked protective effects on renal allografts in patients with long-term lymphocyte depletion by thoracic duct lymph fistulas suggest that both the duration and degree of lymphocyte depletion by this modality are of major importance in the effect on cellular immunity.10,11 In