31 CyA treated renal transplant recipients with biopsy-proven CAN were studied to assess the impact of CyA reduction (50%) and changing from AZA to MMF. All patients received ATG, AZA, prednisone and CyA. When AZA was stopped, 2 g of MMF was given twice daily. 2 week later, reduction of CyA was initiated. The mean creatinine was calculated respectively 0, 6, 12, 24, and 36 months after change. Comparaison of slopes were done by t -student test. 26 patients had sufficient information to provide at least 2-years of follow-up. The mean age was 33+9.8 years. The alteration in IS occurred 21 ± 7.3 months after Tx. 18 of 26 patients had an improvement in the slope of decay of their renal function, whereas only 8 remained the same or deceased. Comparaison of all pre-slopes versus post-slopes showed statistically significant improvement (p < 0.05). Long-time improvement of excretory transplant function is possible in the patients with ongoing CAN by changing from AZA to MMF and reduction of CyA.