The compatibility of cellulose secondary acetate (SAC) and triacetate (TAC) with some synthetic rubbers, possessing different molecular constitution, has been studied. Experimental and theoretical estimation of solubility parameters has been carried out. The obtained data evidence the different compatibility levels in the TAC-based systems. SAC containing systems and synthetic rubbers are uncompatible. The chain structure and molecular mass influence on the rubbers compatibility with cellulose acetate are also discussed. The correlation between the kinetic stability of cellulose acetates and rubber mixture and the data of solubility parameters has been shown. The mean free mixing energy (DELTAg x) has been measured for the TAC and SAC mixtures with some polymers. The negative values of DELTAg x evidence the thermodynamic stability of systems, whereas the positive ones indicate uncompatibility. The method of determining the mixtures surface tension dependence on composition has been proposed to estimate their compatibility. Films from acetate mixtures synthetic rubbers have been obtained and their physico-mechanical properties have been determined.