We conducted a population-based cohort study to compare mortality among 238,292 persons who purchased a handgun in California in 1991 with that in the general adult population of the state. In the 1st year after the purchase of a handgun, suicide was the leading cause of death among purchasers. The increased risk was attributable to an excess risk of suicide with a firearm. As compared with the general population, handgun purchasers remained at increased risk for suicide by firearm for up to 6 years, the excess risk being greater among women than men. (51 refs.)