It has been 40 years since the first demonstration of Lymphocytic Choriomeningitis Virus (LCMV) activity in Argentina, in an almost overlapping endemic area with that of Junin Virus (JUNV), the etiological agent of Argentine hemorrhagic fever (AHF). In this coexistence of at least two arenaviruses pathogenic for man, most data on LCMV activity were circumstantial and discontinuously collected, due to the priority given to diagnostics and treatment of AHF, a disease of high sanitary impact in the region. Important research has been published in the last two decades, recovering focus on the impact of LCMV on the world public health, where data on longitudinal ecological and epidemiological observations are not abundant. This review summarizes information available on LCMV activity in Argentina. Specific antibody prevalence in rodents captured in longitudinal studies, in rural and urban habitats, as well as LCMV strains isolated from them are presented. In human population, data are shown on LCMV antibody prevalence, sequential LCMV-JUNV infection, as well as features of LCM cases and its geographical distribution in the endemic area. Comparisons are also made between Argentine LCMV strains and the Armstrong-WE referential strains of the same virus.