Trend detection in hydrological data has gained importance in connection to global warming. This work intends to contribute to precipitation extreme studies whose importance resides in their applicability in plans of vulnerability and adaptation strategies, since in general droughts and floods produce severe damages to economy and social life. Frequency and intensity variation of extreme rainfall over Tucuman (26.79°S, 65.20°W), a Northwest Argentinean location, is analyzed during the period 1974-2014 in order to detect long-term trends and their possible link to global warming. Mann-Kendall and t tests are used to determine the significance of the trends obtained using ordinary least square and Sen’s non-parametric estimator. The advantages of using Mann Kendall trend statistic are analyzed.