Objective: To determine the sensitivity, specificity, positive predictive and negative predictive value figures (validity) of percentile and percent of median methods versus Z-score. Material and Method: In this study the status of underweight, wasted and stunted children was evaluated by "National Center for Health Statistics" standards and 3 different methods that were percentile, percent of median and Z-score. The Z-score method was accepted as reference test (golden test), and performed the validity analyses of percentile and percent of median results versus Z-score. Results: This study was performed in 300 healthy children under five years of age. Validity of percentile and percent of median methods were tested by sensitivity, specificity, positive and negative predictive values. Sensitivity indicates how successful these methods were in identifying the number of malnourished children, while specificity shows how accurately these methods identify the cases that are well-nourished. It was determined that the sensitivity and negative predictive value for percentile method versus Z-score among underweight are lower than percent of median method. On the other hand the positive predictive value and specificity of percentile are higher than percent of median among stunted. For wasted, the percentile method's sensitivity and negative predictive value are higher and specificity and positive predictive values are lower than percent of median method. Conclusion: As a conclusion we recommend to use the percentile method rather than the percent of median method in monitoring the growth of children.