This paper describes an analysis of annual precipitation trends in Iran. Annual means of rainfall were collected from 39 synoptic stations with reasonable geographic distribution, and with more than 30 years. Trend analysis was investigated by using regression line slope method (annual rainfall as dependent variable and year as independent variable). The results showed that for the longest available period, and at 95% level of significance, 7 stations possessed negative trend, while positive trend has been due to 6 stations. Changing record length to the last 40 years, 4 and 8 stations showed negative and positive trends, respectively. More decrease in record length, up to 30 years, resulted in lower stations to have any significant trend. The results identified that in any case, trend did not depend to mean annual rainfall, but record length could have some effects on it. Based on the results, a climate change is hardly supported

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