In this study we estimated evapotranspiration (ET) using three algorithms based data provided by the images of the TM y ETM+ sensors (Landsat 5 y 7 respectively) and field data for mid-season stage of soybean (January), moment where moisture conditions were optimal. Also, the heat flux soil is negligible. The study site is located on parcel in Tandil (Pampa - Argentina zone-IV). The objectives consisted of applying three algorithms for estimating ET: Model 1: ET Energy Balance; Model 2: ET Adapting Seguir and Itier, and Model 3: ET Priestley-Taylor , and evaluate their performance in relation to the ET obtained by the reference method Penman-Monteith FAO 56 and field data. Results indicate that the methodologies used quantifying with precision the water used by the crop. The methods showed similarities between them. We conclude that any method used allows the estimation of the evapotranspiration with good precision at plot. Algorithm Priestley-Taylor that only data required for application one instantaneous satellite data: net radiation, and one field data: air temperature. We concluded that any method used allows the estimation of evapotranspiration with good precision at plot.