Background: Individuals who use a hookah (water pipe) as a method of tobacco smoking are exposed to high levels of carbon monoxide (CO). Assessing hookah use in one of the venues of its use (hookah bars) will aid the understanding of the toxins and exposure for the user. In Florida, smoking is prohibited in public places under the Florida Clean Indoor Act but permitted in establishments that have less than 10% gross revenue from food. Purpose: To assess the CO level of hookah cafe patrons, using traditional bar patrons as a comparison. Methods: After IRB approval, a nighttime field study of patrons (aged >18 years) exiting hookah cafes and traditional bars in 2009 was conducted, using sidewalk locations immediately outside these establishments in a campus community. As hookah cafes and bars are typically entered and exited in groups, every other group of people exiting the establishment was approached. For comparison purposes, the sample collected was similar in number, 173 hookah cafe and 198 traditional bar participants. Results: Results from analysis conducted in 2010 indicate that patrons of hookah cafes had significantly higher CO levels (mean=30.8 parts per million [ppm]) compared to patrons of traditional bars (mean=8.9 ppm). Respondents who indicate no cigarette use in the past month but had visited a hookah cafe still demonstrated significantly higher CO values (mean=28.5 ppm) compared to those exiting traditional bars (mean=8.0 ppm). Current cigarette smokers also produced significantly more CO if exiting a hookah cafe (mean=34.7 ppm) compared to a traditional bar (mean=13.3 ppm). Conclusions: CO levels are higher for patrons of hookah cafes, for both current and non-cigarette smokers. Although users report that they perceive hookah to be less harmful than cigarettes, the greater CO exposure for hookah users that was observed in this study is not consistent with that perception.