Secondhand smoke exposure is estimated to account for 3,000 cancer deaths per year. Although several countries and states in the United States have passed comprehensive smoke-free laws to protect all employees, a significant number of workers are still not protected. The purpose of this study was to determine the effects of passing a comprehensive smoking ban that included bars and restaurants on biomarkers of nicotine and carcinogen exposure. The urines of nonsmoking employees (n = 24) of bars and restaurants that allowed smoking before the smoke-free law were analyzed before and after the law was passed in Minnesota. The results showed significant reductions in both total cotinine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (free plus glucuronidated) after the ban was instituted. These results provide further support for the importance of protecting employees working in all venues.