According to studies, there is correlation between cyclosporine blood level and function of transplanted kidney, so decrease in drug level may cause acute rejection in graft and its increase is accompanied with graft toxicity. Cyclosporine is regarded as a drug with narrow therapeutic index. It has different bioavailability and pharmacokinetic among people and in different times after transplantation. In this study, we compared the effect of different kinds of detection of drug level (trough versus peak level) on graft function. 106 patients received graft during the research period, 70 of them had criteria of entrance to study, but at the end of study, only 50 cases completed it. Trough (C0) and peak (C2) levels were monitored 7 times during the first 6 months after transplantation. After transplantation, C2 level was increased gradually, while until second week after transplantation, nobody had therapeutic C2 level, after that, only 25.7% of patients had therapeutic C2 level. There was not significant difference in laboratory data between two groups. Acute rejection in graft was observed in only 11 cases that none of them had therapeutic peak level. In conclusion, it was appeared that race may have effect in cyclosporine blood level may be by different metabolism and absorption of drug in Iranian people, so peak level may occur in different time (like 1.5 or 3 or 4 hours after taking the drug).