In this work the aim was to evaluate the performance of the minievaporimeter UFV-1, operating with water at a 30 mm border level, to estimate (ET0) in relation to the lysimeter with constant groundwater table. The minievaporimeter UFV-1 is made of PVC and consists of a tube with internal diameter of 244 mm and 320 mm height. The minievaporimeters and the lysimeters with constant groundwater Table were separately connected to a modified irrigation meter, which was used to keep water at constant level in its interior and measure the amount of evaporated and evapotranspired depth. The evaporation was related to the (ET0) obtained by the lysimeter to obtain minievaporimeter coefficients. In all the analyzed periods of time, the minievaporimeter presented better ET0 estimate than the other methods studied. These results justify the use of minievaporimeter for irrigation water management.