Thrombotic microangiopathy (TMA) is a disease of microvascular. It presents with Thrombocytopenia, microangiopathic hemolytic anemia and tissue ischemia. After renal transplantation TMA may occur as a recurrent form or as a result of calcineurin inhibitors or infection. We retrospectively studied renal biopsy slides of 57 allograft biopsies that were performed within the first two months of renal transplantation. These biopsies were performed in 237 patients in a five years period. (2001-2005), all specimens were stained using hematoxylin and eosin, masson trichrome and periodic acid-schiff. All slides were reviewed by one pathologist for histological findings compatible with TMA. Clinical and laboratory information of these patients were gathered by retrospective review of medical records. Those with significant thrombocytopenia (platletes<100,000/ml), shistocyte on peripheral blood smears or lactate dehydrogenase >1000U/l, called systemic and those without these manifestations defined as localized TMA. The incidence of TMA was 7of 57 biopsy (12%), or 3% in 237 transplanted patients. Five of them (71%) had systemic criteria and two (29%) were localized. three of systemic patients improved with plasma exchange. But one of localized TMA that plasma exchange was not started for him lost his allograft. Two patients with TMA died, one of them had systemic aspergillus and another one had a previous history of liver hydatid cyst. It seems that some of post- renal transplant TMA is renal limited, and allograft dysfunction is their only manifestation. Timely treatment could improve the allograft outcome.