Waterpipe is a tool for smoking tobacco, which is thought to be less harmful than cigarette. Unfortunately, there aren't adequate studies about its harms to health that are threatening the young generation all over the world today. The objective of this study was to show the carbon monoxide (CO) levels in waterpipe smokers' breaths, whether can be used or not to reflect the changes of oxidative stress for this reason to predict harmful effects on the pulmonary functions.