Hookah tobacco smoking is increasing among US college students, including those who would not otherwise use tobacco. Part of hookah's appeal is attributed to the perception that hookah is less harmful than cigarettes. The aims of this study were to assess knowledge of harmful exposures associated with hookah smoking relative to cigarette smoking and to determine associations between this knowledge and hookah smoking outcomes. Students (N = 852) at the University of Florida were randomly sampled via e-mail to obtain information on demographics, hookah smoking behavior and knowledge of five exposures (e.g. tar and nicotine). Multivariable logistic regression models assessed independent associations between knowledge and hookah smoking outcomes. Of the five factual knowledge items asked, 475 (55.8%) of the respondents answered none correctly. In multivariable models, correct responses to any knowledge items were not associated with lower odds of hookah smoking or susceptibility to hookah smoking in the future. Although college students are largely unaware of the toxicant exposures associated with hookah smoking, there is little association between knowledge and hookah smoking behavior.