The aim of this work was to construct probability tables of reference evapotranspiration in mm, accumulated at twenty, fifteen (biweekly) and ten days (decennial) in Mossoró, RN, Brazil, from the daily records of evapotranspiration obtained from the Meteorological Station of the University Federal Rural do Semi-Arid (UFERSA) in Mossoró, RN, using the Penman-Monteith method. No prior transformation of data was necessary, since the construction of the tables is based on the approximation of the variable to Normal distribution. The probabilities were estimated by the Normal distribution for the levels of 1% to 95%. The tables were constructed with data from 1970 to 2007, taking into account the results of the tests of chi square and Kolmogorov-Smirnov at 10% probability. It can conclude of the suitability of the construction of the tables and that these tables represent subsidies important in the planning of the farming and livestock activities in the region, taking the most advantage of its benefits and avoiding its harmful effects
