Women may bear the brunt of domestic violence, but children are also inflicted by the consequences of violence between their parents. We sought to evaluate the lifetime prevalence of exposure to physical violence between parents among some senior secondary school students in Tehran. The study was conducted on senior secondary school students in all 19 educational districts of the Iranian capital, Tehran, in the academic year of 2005-06 using a multi-stage sampling. Data were collected via a self-administered questionnaire. A total of 1,495 students participated in this survey, with the prevalence estimated at 22.8%. More than half of the subjects had witnessed domestic violence between their parents; the prevalence of exposure among the girls was twice that among the boys. The most frequent act of violence was beating the partner with bare hands and the perpetrators of the violent acts were predominantly the fathers. Exposure was long-lasting; and in those with more than one exposure, the mean duration of exposure was 5.1 years. The most prevalent rates of exposure to domestic violence came from Educational Districts 15 and 10. The fact that a considerable portion of the teenagers in the present study had witnessed physical violence between their parents bears testimony to the high frequency of this form of violence in Tehran households. It is noteworthy that the socio-economic status of the families and parental divorce and estrangement increased the likelihood of exposure to domestic violence in our series.