The results obtained in the present article show that the fractal analysis and irreversible aggregation models application allow to obtain a clear physical picture of copolycondensation process and estimate its quantitative characteristics. The basic characteristic, controlling this pro-cess, is fractal dimension D-f of macromolecular coil in solution. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 3026-3030, 2009