This document aims to serve as guidance for biosafety officers, end-users, regulators and inspectors and to provide information on the correct implementation of the necessary containment criteria and other protective measures in laboratory animal facilities in order to guarantee an optimal protection of public and occupational health and of the environment. Quality aspects of animal care falling under laboratory animal welfare regulations will not be considered here. To allow more clarity and a better understanding of the biosafety requirements and recommendations in laboratory animal facilities, various concerns on personal protection and biosafety equipment, facility design, working practices and waste management are addressed in this document, mainly with respect to small animal facilities. Several issues in risk management are discussed and check lists (in annex) describing the containment measures assigned to the different animal biosafety levels (see below) are provided and can be used for internal and external audits. In Belgium, most activities involving animal experiments with transgenic animals or animals inoculated with either pathogens or genetically modified micro-organisms are subject to notification in the frame of regional legislation on contained use of genetically modified organisms (GMOs) and/or pathogens. This legislation transposes European Directive 2009/41/EC, repealing Directive 90/219/EC (EC, 2009). Animal facilities should comply with the containment criteria defined in the legislation for each biosafety level.