A technical update on rat kidney transplantation is given. In this study, the bladder-bladder union was made using silk, polyglycolic acid (Dexon), polyglactin (Vicryl), and chromic catgut. The propensity of these sutures to form vesical calculi was investigated in both first and second generation transplants. The results of our study indicate that there is no significant difference (P greater than 0.01) in their calculogenic ability. Special problems attendant with first and second generation kidney transplants are described. The concept and technique of second generation kidney transplants are also described.