In this study, daily rainfall estimates from IMERG Early, Late, and Final runs (IMERG-E, IMERG-L and IMERG-F) are compared with daily precipitation measured by 22 synoptic rain-gauges of Iran Meteorological Organization (IRIMO) over the northwest and west regions of Iran. Assessment is implemented for a period from April 2016 to February 2017. Statistical indices are computed for two threshold values of 0.1 mm/day to define rain/no rain and 5.0 mm/day as moderate or higher rainfall events. Overall, results reveal that all the three runs tend to underestimate in the second threshold (5.0 mm/day) with Bias less than 1.0; however IMERG-F has much better Bias. Beside that at this threshold IMERG-F has little error, more probability of detection (POD) and Peirce skill score (PSS) than the two others. False alarm ratio (FAR) for the three runs is nearly the same; at the second threshold FAR and POD for IMERG-L are about 0.14 and 0.50 and for IMERG-F are 0.56 and 0.27, respectively. As expected, IMERG-F estimates are supposed to be the most accurate and reliable.