It is well-established that second-hand cigarette smoke affects the health of everyone who is exposed to it. However, second-hand smoke is particularly dangerous for children, increasing their risk of developing asthma, chest infections and triggering asthma attacks. In addition, previous research shows that smoking just one cigarette in a car, even with the window open, creates a greater concentration of second-hand smoke than a whole evening's smoking in a pub. Hence, exposing children to second-hand smoke in a car is exceptionally hazardous. This study sought information regarding children's experiences of, and attitudes towards, being exposed to second-hand cigarette smoke, including exposure in cars. 1001 children aged 8–15 (51% male, 49% female) were surveyed online via a self-completion questionnaire between 20 and 27 January 2011. 51% of respondents had been in a car when someone has been smoking at some time. Of the 512 respondents who had been in a car while someone was smoking, 31% said they would ask them to stop, 24% said they were too embarrassed to ask them to stop, 9% said they were too scared to say anything and 21% said they didn't mind. All respondents were asked how they felt when an adult smokes near them. 58% said it made them smell of smoke, 49% said it made them feel sick, 44% said it made them cough and only 7% said it didn't bother them. 86% of all respondents said they would like the Government to stop people from smoking when children are in the car, with only 4% saying they would not and 10% saying they did not know. This survey shows that an overwhelming majority of children would support legislation to protect children from passive smoke in the car. This work also suggests that when exposed to second-hand smoke while travelling in a car, many children do not feel able to ask the smoker to stop. More work is needed to empower children and give them a voice to help change legislation around smoking in private cars and to increase awareness of the dangers of second-hand smoke.