Working with pathogenic organisms (genetically modifiedor not) requires the adoption of specific containment methods,protective measures, and safe work practices to avoid adverseeffects on human health and the environment. In particular,special containment and protective measures must be adoptedin laboratories where airborne pathogens that may causeserious or potentially high-consequence diseases due to accidentalexposure are handled. Such high-level containmentrefers to laboratories and other facilities (e.g., animal facilities,large-scale production units) at containment levels 3 and 4(CL-3, CL-4). These high-containment facilities are designed forthe diagnosis, surveillance, and control of infectious diseases,for the study of pathogenic organisms, and for the preparationof vaccines. These high-containment facilities, therefore, playa critical role in ensuring a safe environment for workers andin protecting public health and the environment.This article presents data received from notifications andreviews the progress achieved with the high-containment facilitiesin Belgium over the last 18 years. Since no CL-4 facilitiesexisted in Belgium at the time of this study, this article relatesonly to CL-3 facilities. A critical review of the progress achievedwithin this area of activity is also provided.