Smoking among partners of non-smoking pregnant women has been linked to adverse pregnancy outcome, including low birthweight. Paternal smoking also increases the risk of infant respiratory infections and sudden infant death syndrome, irrespective of maternal smoking status. Furthermore, men's smoking habits are probably one of the strongest influences on the extent to which women are able to quit smoking in pregnancy and maintain cessation post birth. In four focus group discussions, male smokers whose partners were pregnant discussed their beliefs about passive smoking in pregnancy, the barriers they perceived to quitting in pregnancy and their preparedness to support maternal cessation. Men were largely unaware that their own smoking could pose a specific risk to the fetus, but when pregnant women are smokers, men believed their own smoking habits were unimportant. For men, barriers to quitting during their partners' pregnancy were: lack of understanding as to how passive smoking can affect the fetus, including a belief that the fetus is "protected" inside its mother; lack of motivation to quit early in pregnancy due to the baby not being "real"; and concern about stress-induced marital discord associated with cigarette withdrawal. These findings are discussed with regard to messages and strategies which may influence men to quit during their partners' pregnancy.