To investigate a possible association between firearm regulations and suicide, we compared the incidence of suicide from 1985 through 1987 in King County, Washington, with that in the Vancouver metropolitan area, British Columbia, where firearm regulations are more restrictive. The risk of death from suicide was not found to differ significantly between King County and the Vancouver area (relative risk, 0.97; 95 percent confidence interval, 0.87 to 1.09). The rate of suicide by firearms, however, was higher in King County (relative risk, 2.34; 95 percent confidence interval, 1.90 to 2.88), because the rate of suicide by handguns was 5.7 times higher there. The difference in the rates of suicide by firearms was offset by a 1.5-fold higher rate of suicide by other means in the Vancouver area. Persons 15 to 24 years old had a higher suicide rate in King County than in the Vancouver area (relative risk, 1.38; 95 percent confidence interval, 1.02 to 1.86). Virtually all the difference was due to an almost 10-fold higher rate of suicide by handguns in King County. We conclude that restricting access to handguns might be expected to reduce the suicide rate in persons 15 to 24 years old, but that it probably would not reduce the overall suicide rate.