Abstract: The performance of 2 models for estimating monthly energy limited Evapotranspiration (E_e) was compared for the tropical humid region of the rainforest belt of Nigeria. The models are Thornthwaite, which depends on temperature as the only parameter input and Hargreaves, which utilizes solar radiation and air temperature input. The reference data were obtained from the International Institute for Tropical Agriculture, Ibadan, Nigeria. Performance analysis for the estimated values of the collected meteorological data was made. The Standard Error of Estimate (SEE) and the model error were calculated both on monthly and seasonal basis. The estimated values were correlated with the observed values from lysimeter and it was found that Thornthwaite and Hargreaves models have correlation coefficients of 0.65 and 0.77, respectively and 0.93 and 0.89, respectively in dry season; both have the same coefficient of 0.98 for wet season. The SEE for Thornthwaite and Hargreaves are, respectively 0.68 and 0.90. On the model error for the 2 models, it was found that Thornthwaite gives a smaller error of about -1.22% (i.e., underestimation of about 1 mm yr ¹) compared with Hargreaves which is 9.28% (having an overestimation of 4 mm yr ¹). Both methods have high significant correlations but Thornthwaite�s has a better SEE compared with Hargreaves, except for its overestimation during the dry and underestimation in wet season. The two models, if properly calibrated for the environment in question, are recommended for use as practical methods for estimating energy-limited evapotranspiration when considering the availability and reliability of the input data.