In the long-term storage of energy wood chips can arise risk which threaten the workforce health as well as stored substance. The main thesis aim is the analysation of biological risks influence on long-term storage of energy wood chips. The thesis interprets basic characteristic and diversity of biomass. Also describes actual state and perspective in the field of using biomass, ways of biomass using, ways of wood chips storage, potential risks which can arise in the long-term storage and characteristics of most often identified microorganisms in wood chips. The laboratory microorganism identification from four different locations situated in Slovakia is also part of thesis. 18 microorganism species was identified from samples. The thesis result is evaluation of microorganism variation from two periods and also their influence on human organism. Number of microorganism species increased and also average number of microorganism was major in comparison with previous period.