The validation of suggested pharmacohore model, Hypo1, was performed by two different validation methods, namely, test set prediction and Fischer randomization methods. A test set containing 97 compounds, representing diverse activity classes and different functional groups, is used in this validation process. These test compounds were imported into the DS and diverse conformers were built in the same manner as for training set compounds. The estimated activities of these test set compounds were calculated based on the geometric fit of these compounds over Hypo1. Analyses of the estimated activities of test set compounds demonstrated remarkable results. From the 97 test set compounds, 94 compounds showed error values less than 5 which is hardly different from the experimental and estimated activity values (Table 3) . Eight out of nine of the most active compounds were estimated in the same activity scale, whereas the ninth compound was predicted as moderately active. Seventeen out of 26 moderately active compounds were estimated in the same scale, whereas the remaining nine were estimated as less active compounds. All the 40 less active compounds were estimated in the less active scale. Furthermore, only three of the 22 inactive compounds were predicted as less active compounds. Thus, the ability of Hypo1 to forecast the activity of test set compounds was very impressive and outstanding. A correlation value of 0.928 was achieved between experimental and estimated activities of test set compounds. A correlation plot showing the correlation between the experimental and estimated activity values of training and test set compounds was generated and displayed in Figure 6 . 