Aim: To observe the effects of fathers’ smoking on respiratory symptoms in children between theages of 6 mo and 5 y living in Tehran during the period January to December 2001. Methods: Thecaregivers of 622 children attending resident-based clinics in two university hospitals wereinterviewed about the respiratory illnesses incurred by the child during the previous 12 mo and thesmoking habits of those living with the child. Children who lived in households in which anyperson, other than the father, smoked were excluded. Results: The analysis included 595 children,40.6% of whom were living in homes where fathers smoked cigarettes. About 35% of smokersadmitted to unrestricted smoking at home. In children not living with a smoker, 81.6% hadexperienced at least one episode of upper respiratory tract infection (URTI) during the previousyear and the rate increased to 95.2% in passive smokers whose fathers were not restricted fromsmoking in front of the children, (p-value 0.01). A similar pattern was found for otitis media andasthma (p-value 0.05 and 0.01, respectively). The average number of URTI episodes duringthe previous year was significantly higher in children exposed to unrestricted smoking (p 0.01).Conclusion: The study outlines the detrimental effects of paternal smoking on the respiratoryhealth of children from a part of world in which this problem has not been studied previously,and highlights the importance of educating fathers to alter their smoking habits so that even ifthey do not stop smoking altogether, they should discontinue smoking indoors