This study is designed to evaluate the prevalence of waterpipe tobacco smoking and its related factors among Iranian adults. This is a cross-sectional study carried out during 2013/14 in Tehran, Islamic Republic of Iran, among 1830 citizens aged over 15 years. Sampling was through Stratified multistage cluster sampling with proportional allocation within strata. Global Adult Tobacco Survey (GATS) questionnaire for waterpipe consumption was used for data gathering. Data were statistically analyzed by SPSS software. The prevalence of current waterpipe tobacco smoking was 17.6% .Waterpipe use prevalence in men was significantly more than women (24.2% vs. 11.3%). Multivariate analysis showed that age, sex, cigarette consumption, waterpipe consumption at home and ignorance of safety issues significantly influenced current waterpipe smoking (P = 0.001). Thus, prevalence of waterpipe smoking in Iranian adults is high and significant. Tackling waterpipe smoking should be considered in tobacco control programmes. However, further studies in this field are needed.