OBJECTIVE: To determine if any of five different state gun laws were associated with firearm mortality: (1) "shall issue" laws permitting an individual to carry a concealed weapon unless restricted by another statute; (2) a minimum age of 21 years for handgun purchase; (3) a minimum age of 21 years for private handgun possession; (4) one gun a month laws which restrict handgun purchase frequency; and (5) junk gun laws which ban the sale of certain cheaply constructed handguns. DESIGN: A cross sectional time series study of firearm mortality from 1979 to 1998. SETTING: All 50 states and the District of Columbia. SUBJECTS: All residents of the United States. MAIN OUTCOME MEASURES: Firearm homicides, all homicides, firearm suicides, and all suicides. RESULTS: When a "shall issue" law was present, the rate of firearm homicides was greater, RR 1.11 (95% confidence interval 0.99 to 1.24), than when the law was not present, as was the rate of all homicides, RR 1.08 (95% CI 0.98 to 1.17), although this was not statistically significant. No law was associated with a statistically significant decrease in the rates of firearm homicides or total homicides. No law was associated with a statistically significant change in firearm suicide rates. CONCLUSION: A "shall issue" law that eliminates most restrictions on carrying a concealed weapon may be associated with increased firearm homicide rates. No law was associated with a statistically significant reduction in firearm homicide or suicide rates.