This population-based case–control study of North Carolina workplaces evaluated the hypothesis that employers’ policies allowing firearms in the workplace may increase workers’ risk of homicide. Workplaces where guns were permitted were about 5 times as likely to experience a homicide as those where all weapons were prohibited (adjusted odds ratio=4.81; 95% confidence interval=1.70, 13.65). The association remained after adjustment for other risk factors. The findings suggest that policies allowing guns in the workplace might increase workers’ risk of homicide.