Abstractfor long time, calcineurin-inhibitors (CNIs) was the best broadly used immunosuppressant in organ transplantation; since it had proven its efficacy in the reduction of acute rejection episodes and early graft loss, though their use in the long-term, are associated with chronic allograft nephropathy (CAN), besides it increases the cardiovascular risks such as diabetes, hypertension, and dyslipidemias. Moreover, CNIs in combination with other immunosuppressant's increases the risk of fatal infections and malignancy. Ultimately the introduction of the mammalian focus of rapamycin (mTOR) inhibitors, such as sirolimus and everolimus in 1990s, had changed the face of transplantation and conveyed a great hope to transplant physicians as an innovative class of effective immunosuppressants with a unique mechanism and less nephrotoxic effects (1-6).In this review article we will try briefly to elicit the clinical indications, advantage and disadvantage of m-TOR inhibitors over other immunosuppressant's medications and their clinical indications inside and outside the transplant field.