The aim of this study was to evaluate predictive performances of CHAID, Exhaustive CHAID, and CART regression tree methods for different combinations of parent node: child node in the data set regarding animal science. To achieve the aim, 1884 Mengali lambs were provided for predicting weaning weight from sex (male and female), birth type (single and twin), birth year (2005, 2006, 2007, 2008 and 2009), farm (Research station, Mastung, Quetta, and Noshki), birth weight, dam age, and dam weight. To choice the best regression tree method, goodness of fit criteria such as coefficient of determination (R 2%), adjusted coefficient of determination (Adj-R 2%), coefficient of variation (%), SD ratio, relative approximation error (RAE), Root Mean Square Error (RMSE), Pearson correlation between actual and predicted weaning weights were estimated for each combination. It was determined that CHAID algorithm constructed more suitable tree structures, biologically in comparison to Exhaustive CHAID and CART data mining algorithms. Consequently, it is recommended that the biological suitability of the constructed tree structure should be taken account together with estimating model quality criteria.