National Institute for Public Health (RIVM), Bilthoven, is a recognised leading centre of expertise in the fields of health, nutrition and environmental protection, which works mainly for the Dutch government. It also shares knowledge with other governments and supranational bodies around the world. The results of the research, monitoring, modelling and risk assessment are used to underpin policy on public health, food, safety and the environment. RIVM has over 1400 employees, many working in multidisciplinary fields. The Microbiological Laboratory for Health Protection (MGB) group is part of the Centre for Infectious Disease Control of RIVM. The laboratory has about 50 employees who perform research, consultancy and diagnostics in the field of human pathogenic microorganisms, including zoonoses and deliberately introduced microorganisms. The laboratory works as a reference laboratory. It investigates the risks for humans and the environment caused by microorganisms in food, animal, water and soil. The main assignment is to develop and implement methods for quantitative microbiological risk assessment. A secondary task is the devise of new diagnostic and mathematical tools for quantitative microbiological risk assessment. All research projects combine experimental, observational and model-oriented methods where possible. (Annemarie Pielaat, Bart van Rotterdam, Arie Havelaar)