The presence of biological agents in the workplace may result in hazardous situations for workers. The present study was carried out in the microbiology laboratory of a Medical School and the methodology was based on the qualitative method presented in the Technical Note of Spanish Prevention (NTP 833) and the Accompanied Method of Biological Risk Management (MAGRB). It was concluded that the MAGRB allows to distinguish and prioritize the risk associated to the different operations as a whole, taking into account safety conditions and practices, if evaluation parameters defined in the legislation of bio-logical agents are met, something that the International method (NTP 833) does not allow doing so effectively. As the focus of worker protection, the MAGRB provides the necessary guidelines to trigger a prevention structure in all ac-tivities likely to be exposed to biological agents.