A new lnethod is presented for the calculation of octanol/water partition coefficients.On the basis of summation of atomic contributions, our algorithm, namely;XLOGP, also incorporate correction factors into the calculation. Multivarlate regression aIlalysis was performed on a traming database of 1831 organic compounds with diverse structures to give the final model. The correlation coefficients for the whole set fitting is 0.968 and the standard deviation is O.37. The result sllows that our model is accturate enough for logP estmimation in QSAR studies. Compared to other similar approashes, our method gives better results and is more convenient to use.