The risks & benefits of owning a firearm are discussed. Study design issues that must be considered when studying this issue are considered. Problems & benefits of case-control, ecologic & cohort studies are discussed as well. Six case-control studies are mentioned, with all 6 reporting that the relative risk of suicide was higher in homes with guns. Some studies distinguished type of gun, length of ownership, & multiple guns in households as well, which the authors note. (17 refs.)