In this work, we described the LogKow program that estimafe-s the log octanol/water partition coefficient (log P) of organic chemicals using a atorn/fragmental method developed at SRC. Chemical structures can be brought into LogKow estimation program using SMILES notation, CAS RN or commercial drawing programs that allow a user to draw a chemical structure and then directly write the SMILES notation. SMILES is an acronym for Simplified Molecular Input Line Entry System. It is a chemical notation system used to represent a molecular structure by a linear string of symbols. A two-dimensional drawing of a single chemical structure is possible in many different forms. That is, a single structure can be depicted correctly by many different SMILES notations. SMILES notations are comprised of atoms (designated by atomic symbols), bonds, parentheses (used to show branching), and numers (used to designate ring opening and closing positions). The SMILECAS Database is very helpful and time-efficient in obtaining SMILES notations and log P values; all that you need is CAS Reigistry Number. This database contains the SMILES notations for 103 000 compounds. In order to evaluate this method estimated log P values were compered with these experimental obtained from the SMILECAS Database. Statistical analysis has been performed using the StatSoft Inc.1992. Microsoft Corp. program. Results show that there was no statistical significant difference, p<0.999. Using LogKow, the user can save time and energy because the program can be used as substitute for time-consuming experimental methods. LogKow is even suitable for calculating lipophilicity of very hidrophilic and lipophilic compounds which can't be measured experimentally.