Background Because the presence and improper storage of household firearms are risk factors for injury, it is important to understand the prevalence of ownership and storage practices within households to help guide intervention development. This systematic review of published articles (1992 to 2002) provides prevalence estimates of firearm ownership and storage practices in U.S. households. Methods A search of bibliographic databases (MedLine, CINAHL, PsycInfo, Sociological Abstracts) was completed in January 2003. Results Although all were cross-sectional, the 42 articles included in this review varied in type; there were seven national and five state prevalence studies, as well as studies using clinic-based convenience samples (n =14) and samples of professionals (n =10). Published studies indicate that firearms are present in about one third of U.S. households. Handguns in particular are present in more than half of U.S. households with firearms, or about 19% of all U.S. households. The prevalence of firearms and handguns in households with young people was similar to the prevalence overall. Firearm ownership was highest in the South. Conclusions Although the methodologic rigor of published articles varies substantially, the literature clearly establishes that firearms are common in U.S. households, even in the homes of medical professionals and those with children. © 2004 American Journal of Preventive Medicine.