Carboxylates and their antimony(III) complexes experimentally scanned earlier for antileishmanial activity (IC50) against five leishmanial strains viz., L. major, L. major (Pak), L. tropica, L. mex mex, and L. donovani. These activities have been theoretically predicted by DFT method along with quantitative structure-activity relationship (QSAR) study. Molecular modeling and geometry optimization of the all the eight compounds have been performed on workspace program of CAChe Pro software of Fujitsu by opting B88-PW91 (Becke '88; Perdew & Wang '91) GGA (generalizedgradient approximation) energy functional with DZVP (double-zeta valence polarized ) basis set in DFT (Density Functional Theory). For QSAR, multiple linear regression (MLR) analysis has been performed on Project Leader Program associated with CAChe. The reliability of correlation between experimental activities and predicted activities are r 2 = 0.826, r 2 CV = 0.426 (L. major); r 2 = 0.905, r 2 CV = 0.507 (L. major (Pak)); r 2 = 0.980, r 2 CV = 0.932 (L. tropica); r 2 = 0.781, r 2 CV = 0.580 (L. mex mex) and r 2 = 0.634, r 2 CV = 0.376 (L. donovani), and a comparison of the experimental values and the values obtained by theoretical calculations has been presented pictorially that shows close resemblance.