One of the causes of kidney graft dysfunction is renal fibrosis. Myofibrobtastes (aSMA) have a role of fibroblasts activation. The study was to measure the appearance of aSMA on 56 biopsies of 15 renal transplant patients at Rangueil Hospital, France from 1/1/2006 to 31/12/2008. The results of study showed that presence of aSMA was higher on clamp groups than other groups (p 0.01). aSMA was highest in "other cause" group. The appearance of aSMA was decreased and 5 years after these patients receiving dialysis. In conclusion, the aSMA appeared after renal transplantation and higher when there was a renal dysfunction and when 'it reduced, have a poor prognosis for renal transplantation.