Since the mid-1980s there has been increasing interest in the effects of passive smoking on the health of children. It has been estimated that the total nicotine dose received by children whose parents smoke is equivalent to their actively smoking between 60 and 150 cigarettes per year. This review article considers the evidence for a relationship between passive smoking and disorders such as: prenatal damage to the fetus; poor growth indicators; respiratory illness; atopy and asthma; coronary heart disease; and sudden infant death syndrome. We conclude that paediatricians should not be complacent about the hazards of passive smoking for children and that public health education efforts should be continued.