The influence of operating parameters such as bead loading, peripheral velocity and bead size on the kinetic behavior of cell disruption in a bead mill was investigated. The bead mill was equipped with a single rotating disc and operated batchwise. Analysis of the data showed that the frequency of bead collision may be correlated to the observed first-order process, applying a new concept called effective disruption volume. It was found that the first-order rate constant was proportional to the square of bead loading within the other experimental conditions examined and increased with the decrease in bead diameter. A new disruption kinetics was proposed, explaining all the observed data in terms of the frequency of bead collision and the concept of effective disruption volume. Although other types of microorganisms were not examined, the concept may well be extended to various kinds of cells.