Lymphocytic choriomeningitis virus (LCMV) is an enveloped, ambisense RNA virus and the prototypic virus of the arenavirus group. It can cause viral meningitis and other ailments in humans, but its natural host is the mouse. The LCMV/mouse model has been useful for examining mechanisms of viral persistence and the basic concepts of virus-induced immunity and immunopathology. This unit discusses strain differences and biosafety containment issues for LCMV. Recommendations are made for techniques for propagating LCMV to high titers to quantify it by plaque assay and PCR techniques and to preserve its infectivity by appropriate storage.