Background. The aim of protocol biopsy after renal transplantation was to assess the prevalence of chronic allograft nephropathy (CTN) and to correlate the degree of CTN with clinical and laboratory data. Methods and Results. In 105 patients with a stabilized graft function, a protocol biopsy was carried out at 1 year after transplantation. CAN was found in 75% of patients, and in 6% an acute subclinical rejection was revealed. Statistically significant correlation was confirmed between CAN and recipient’s age, development of acute rejection in the first year posttransplant, serum creatinine, clearance of creatinine, and proteinuria. There was no significant difference in CAN degree distribution between patients treated with cyclosporine-A or with tacrolimus. Twelve months after the biopsy, there was no significant change in kidney graft function. In patients treated with tacrolimus, cholesterol and triglycerides levels were significantly lower than in cyclosporine treated patients Over the next year, these values significantly decreased in both subgroups. Conclusions. The CAN was found in the majority of protocol biopsies at 1 year after kidney transplantation; subclinical acute rejection was revealed rarely.

        Key words: graft biopsy, acute rejection, chronic rejection, chronic allograft nephropathy, tacrolimus, cyclosporine- A.