The use of empirical relationships for the calculation of the energy and aerodynamic components of the Penman-Monteith equation were tested against measured data. Accurate estimates of maximum total evaporation, Em, from a wheat crop were obtained. The empirical equation utilizes measured or estimated total radiation flux density, St, in the energy component, plus evaporation from a screen Pichéatmometer to account for aerodynamic influences. The agreement of estimated Em versus lysimetrically measured Em was good. The high index of agreement of 0,98 and a low mean absolute difference of 0,51 mm over the daylight period were obtained with St measured. When St was estimated, using an appropriate formula, these statistics were 0,98 and 0,57 mm, respectively.