The use of firearms is a common means of suicide. We examined the effect of a policy change in the Israeli Defense Forces reducing adolescents' access to firearms on rates of suicide. Following the policy change, suicide rates decreased significantly by 40%. Most of this decrease was due to decrease in suicide using firearms over the weekend. There were no significant changes in rates of suicide during weekdays. Decreasing access to firearms significantly decreases rates of suicide among adolescents. The results of this study illustrate the ability of a relatively simple change in policy to have a major impact on suicide rates.