Objective: Sirolimus (SRL) have been pointed as a feasible option for minimize the use of Cyclosporin A (CsA), especially because of putatively less nephrotoxicity. This study aimed to characterize the histological lesions and the molecular pathways implicated in CsA-induced nephropathy and prevention when converted to SRL. Method: The following 4 groups (n=6) were tested during 9 weeks: Vehicle, CsA, SRL and Conversion (CsA 3 weeks + SRL 6 weeks). BP and HR were monitored. Blood was collected and kidney gene expression of markers of inflammation, proliferation, angiogenesis and oxidative stress were assessed. Histology: H&E, PAS and Gordon & Sweets staining. Statistics: ANOVA and Post´hoc tests (p<0.05).