Pig slurry is one of the production manure, which should be managed properly because of environmental threats it can cause. Pig slurry contains a wide range of microorganisms, most of which are opportunistic or obligatory pathogens for people and animals. Spreading it on fields without control can cause microbial contaminations of water and soil. Use of pig slurry as substrate in anaerobic digestion can be an effective way of sanitization. In this work role of methanogenic fermentation in pig slurry sanitization was laboratory examined. Study materials were biological samples: 1 sample of raw slurry and 3 samples of fermented biomass from different stages of fermentation. Total number of coliforms was determined by MPN (most probable number) method, and presence of enterococci was verified in each sample. Study have shown that anaerobic digestion reduced total number of coliforms from initial amount of 7.0 x 106 [MPN/ml] in raw slurry to 3.7 x 104 [MPN/ml]. Total reduction was 99.47%. Moreover, after first fermentation, enterococci in the sample were undetectable. Results of this study proved anaerobic fermentation to be an affective way to neutralize microbial threat, that is pig slurry.