The utilization of cell culture systems for propagation of human or simian immunodeficiency viruses constitutes a necessary element in a wide variety of AIDS-related projects. The goal of this core, consisting of a staffed biohazard containment facility, is to support work with infectious materials under safe conditions. The present facility includes 10 individual fully equipped workrooms, ultracentrifuges, fluorescent microscope an autoclaves. The facility is currently utilized by 49 investigators. A Containment Suite Manager and a full-time technician contribute to the operation and maintenance of the Core as well as to the scientific services offered. The Biohazard Containment Facility and staff allow: 1) Training of research personnel in safe handling of infectious materials. 2) The establishment of working conditions in which scientific progress can be expedited without sacrificing worker safety. 3) Technical Support in the preparation/propagation of virus stocks, characterization of the phenotype of virus variants, and testing the toxicity and efficacy of potential antiviral agents. 4) Facilitation of collaborative interactions between investigators experienced in the propagation of primate immunodeficiency viruses and other investigators.