In the third article in this series which mainly assesses the knowledge of school children on the harmful effects of smoking, findings showed that the majority (90%) of school children surveyed were aware of the harmful effects. Current smokers appeared to be the least knowledgeable (69.4%) whilst non-smokers (89.3%) and experimenters (93.7%) were the most knowledgeable. Lung cancer (49%), smoking is bad for health (25%), smoking is bad for passive smokers (7%) and for heart disease (6%) were the most common responses given by the children on the specific ill effects caused by smoking. Smokers and non-smokers alike agreed that smoking is addictive, the proportions agreeing, once again, being lowest among smokers and highest among non-smokers. This trend was also observed when respondents were asked for their attitudes towards smoking--whether cigarette smoking was harmful and whether smoking made a person popular. The majority of respondents felt that a boy or girl who smoked "looked bad"--39% thought so of boys, while a higher proportion (55%), had the same impression of girls. The main reasons for giving up smoking given by ex-smokers were its harmful effects on health (49%), there being no more "kick" to it (16%), peer pressure (13%) and the disapproval of parents and teachers (13%). Among current smokers, at least half stated that they would like to stop smoking. Most of them had tried to kick the habit before but failed in their attempts. Finally, among the non-smokers, only 0.4% of boys and 0.1% of girls indicated that they might smoke in the future.