Mechanical cell disintegration and its influence on anaerobic digestion was investigated using four different methods. Methods to describe the degree of cell-disruption were developed and the release of organic components into the sludge water was measured. The best results were optained using a stirred ball mill and a high-pressure homogenizer. The influence of disintegration rate and digestion time on the performance of the anaerobic process and the dewatering characteristics were investigated. The degradation is accelerated and the digestion time can be reduced, especially when using immobilised microorganisms. It could be shown that the mechanical disintegration results in a disruption of particle structure and an increase of polymer-demand. As a result of better anaerobic degradation the density and dewatering results of disintegrated sludges are improved in comparison to non-treated sludges.