In this paper annual and seasonal precipitation trends of some 48 meteorological stations of central region of Iran during 1971-2000 period were investigated using Mann-Kendall and Sen's Estimator Slope methods. Results show that the application of these two methods is almost similar. the Sen's Estimator Slope method showed better performance where the number of zero in the time series of data was considerable. The results showed a significant negative trend in both test in some of the time series. But no significant positive trend for both test was confirmed. Since the number of series with significant trend comparing with series without any trend was small, therefore a general trend can not be attributed to the region
