Abstract: In design of lead compounds, the rational choice of a few substituents with-out intensive collinearities among the chemical structural parameters for an initialsynthesis is very crucial for obtaining the maximum of information of SAR. 103Common aliphatic substituents have been successively clustered into 5, 10 and 20 clusters with respect to various physicochemical parameters of substituents such as Fr, HA, HD, MR and F by cluster information analysis, the dendrogram classification being given. Thus, selection and preparation of derivative from each cluster based on bioorganic reaction mechanism, drug metabolism, or ease of synthesis will give a maximum range in pararneters and help to establish SAR equation more rapidly. The information contents calculated from Shannon's equation for chemical structural parameters are used as the criterion of matrix contraction.