Background: Prediction of mesiodistal widths of unerupted permanent teeth in a specific group of population requires a valid mixed dentition analysis method as tooth dimensions vary with race, gender and ethnicity. Aim: To evaluate the applicability of Tanaka –Johnston’s & Melgaco’s regression equations and to derive new regression equations in predicting the mesiodistal widths of unerupted permanent canines and premolars among Nalgonda population. Materials and methods: A total of 200 children (100 females and 100 males) who have met the selection criteria were included to appraise the applicability of two mixed dentition space analysis MDSA) methods, Tanaka- Johnston’s and Melgaco’s regression equations among Nalgonda population. Statistical analysis was done using correlation coefficients, independent ‘t’ test, paired ‘t’ test, and ANOVA methods