Background:
In spite of increasing prevalence of concomitant use of water pipe and cigarette there is no enough information in this field. So the concomitant use of water pipe and cigarette and its comparison to only cigarette smoking were evaluated in this study.

Methods:
This cross-sectional study was carried out through stratified multistage sampling in several districts of Tehran. The trained interviewers collected the data about water pipe and cigarette smoking by going to the houses randomly.

Results:
The study had 1830 participants among which 243 participants only consumed water pipe, 120 cases only smoked cigarette and 76 cases (4.2%) were dual users.There was no significant difference in both groups by sex. The mean age of dual users and exclusive cigarette smokers were 33.1±11.3 and 46±16.5 years respectively (p≤0.001).
Comparing to cigarette smokers (35.2%), most of the dual users (64.7%) believed that water pipe is not addictive (p=0.001). 13.2% of dual users and 5.3% of cigarette users believed that water pipe smoking is safer than cigarette smoking(p< 000). While 54.1% of dual users and 78.5% of cigarette smokers believed that waterpipe consumption could cause serious diseases.

Conclusions:
Younger age and misconception about safety of water-pipe in comparison to cigarette were significantly more in dual users than exclusive cigarette users. It is necessary to promote the knowledge about harms of water-pipe smoking in society especially among youth.