The effect of the length of hemodialysis on the outcome of renal transplant was evaluated in 43 recipients of renal allograft. 22 out of 23 patients (95.7%) dialyzed for longer than one year had an excellent renal function at one year, while only 10 out of 20 patients (50%) dialyzed for less than one year had good renal function at one year. Only one kidney (4.3%) was lost due to rejection in the first group, while 10 kidneys (50%) failed to function because of severe rejection in the second group. The length of hemodialysis appears to have a beneficial effect on graft survival, but the mechanism by which it exerts this effect is not clear.