Due to the importance of precipitation data in different fields and also lack of widespread and proper rain gauge networks, the precipitation data should be somehow estimated. Satellites are one of the best apparatus which can use to prepare the required precipitation data. However, it is essential to evaluate the accuracy of such data before using them. The main target of this paper is to evaluate the accuracy of CMORPH and TRMM 3B42RT V7 precipitation data, in Gorganrood Basin, IRAN. To achieve this aim, data of both above mentioned satellites are compared with observation data from six stations including; Tamr, Ramiyan, Bahlakeh, Dashlei, Gorgan Dam, Fazel Abad and Ghaffar Haji, for periods of 2003 to 2007. Moreover, different probability criteria such as; Correlation Coefficient, Mean Bias Error, Root Mean Square Error, CV (Coefficient of Variation) of Root Mean Square Error, Relation Bias Criteria, Probability of Detection, False Alarm Ratio and Critical Success Index were calculated for both satellites. Results show that the studied satellite’s data in monthly and seasonal scales are more accurate than daily scale. The highest correlation between TRMM 3B42RT V7 and CMORPH data comparing to their relevant observed data is related to the August precipitation in “Ghaffar Haji” station, which are equal to 0.93 and 0.85, respectively. Also, the results show that both TRMM 3B42RT V7 and CMORPH satellites estimated precipitation lower than observed data. Also, Probability of Detection and Critical Success of CMORPH satellites are better than TRMM 3B42RT V7. However, False Alarm of TRMM 3B42RT V7 satellite is better.