The Saccharomyces cerevisiae baker yeast microorganisms were disintegrated in a horizontal bead mill to study the relationship between the release of intracellular compds. and cell wall disruption depending on the size of microorganisms. The concn. of the microorganism dry mass in the suspension was 0.002 g/cm(3). The continuous phase of the slurry was an aq. soln. of 0.15 M NaCl and 4 mM K2HPO4. Kinetics of cell disruption were detd. by the no. of live microorganisms. The degree of protein release was detd. by the Bradford method. The yeast disintegration rate increased with increasing the cell size. The process model based on min. diam. (ellipsoidal cell model) was more efficient than the mean diam.-based model (spherical cell model).