Lymphocytic choriomeningitis virus (LCMV) is an arenavirus that causes human disease ranging from a mild, flu-like illness to meningitis. Infections occur principally in and around the home due to contact with infected mice. Data on the incidence of LCMV infection in the United States are scarce but suggest that the risk of infection may have decreased over the past 30-40 years. To examine this hypothesis, sera from an age-stratified sample of hospital patients in Birmingham, Alabama were tested for LCMV antibody by ELISA. The overall prevalence of LCMV-specific IgG was 3.5% (56 of 1,600). The prevalence of antibody among those < 30 years of age was 0.3% (2 of 600), while the prevalence among those 30 years of age and older was 5.4% (P < 0.0001). Multiple logistic regression was used to identify risk factors for LCMV seropositivity. Age was positively associated (P < 0.0001) and socioeconomic status was negatively associated with a positive antibody test result (P < 0.03). These data are consistent with a decreased incidence of human LCMV infection in Birmingham over the past 30-40 years.