The analyses of the spatial and temporal trends of rainfall are very important for the future development and sustainable management of water resources of a given region. Annual and seasonal rainfall data for 36 meteorological stations of Iraq (1981–2010) were analyzed to determine the spatial and temporal trends and determine the significant trends and the magnitude of the rainfall trends by using the Mann–Kendall. Over the 30-year period, negative trend in annual rainfall occurred at 32 sites (88%), while just four sites had positive statistically significant trends. The magnitude of the significant negative trends of annual rainfall at the 95% confidence level varied from (−) 0.227±0.18 mm/year at Basra station to (−) 7.51±1.64 mm/year at Sulaymaniyah station. The change points of the annual rainfall at Sulaymaniyah and Basra stations were 1999 and 1993 respectively. In the seasonal series, the negative trends in spring and winter rainfall were larger compared with fall season trends so that, eight significant negative trends were detected in the spring time series. A noticeable decrease in the winter rainfall series was observed middle region towards Anah, Hadithah and Heet western Iraq.