INTRODUCTION Waterpipe smoking is harmful and addictive and can be a gateway to cigarette smoking. This study examined the association between curiosity and susceptibility to cigarette smoking among cigarette-naïve US youth who smoke waterpipe using cross-sectional data from the National Youth Tobacco Survey, 2014. METHODS Susceptibility to cigarettes was assessed using a composite index of three questions: 'Do you think you will smoke a cigarette in the next year?', 'Do you think that you will try a cigarette soon?', and 'If one of your best friends were to offer you a cigarette, would you smoke it?'. Curiosity was assessed by one question: 'Have you ever been curious about smoking a cigarette?'. RESULTS Among current waterpipe smokers, 48.5% (95% CI: 43.1-53.9) were susceptible to cigarettes and 42.6% (95% CI: 36.5-48.9) were curious about cigarettes. Overall, 45.1% (95% CI: 38.9-51.4) and 46.5% (95% CI: 40.2-52.8) of those living with a waterpipe smoker were susceptible and curious about cigarettes, respectively. Current waterpipe smokers had significantly higher odds of susceptibility to cigarettes (aOR=1.5, 95% CI: 1.1-2.3, p<0.04), but not for curiosity about cigarettes (aOR=1.2, 95% CI: 0.83-1.70, p=0.3). CONCLUSIONS Initiation of cigarettes among adolescents who smoke waterpipe can be due to increasing susceptibility to cigarette smoking rather than increasing curiosity about cigarettes.