OBJECTIVE To examine the association between breakfast consumption and physical activity in a well-characterised sample of English children. METHODS Cross-sectional study using food diaries to record breakfast consumption and accelerometry to assess physical activity. METHODS Norfolk county, England. METHODS Children (n 1697) aged 9–10 years from the SPEEDY (Sport, Physical Activity and Eating behaviour: Environmental Determinants in Young people) study. RESULTS Boyswho consumed a poor-quality breakfast based on dairy product, cereal and fruit intakes spent approximately 7 min more time in moderate-to-vigorous physical activity (MVPA) during weekday afternoons and evenings compared with those who did not consume breakfast (P,0?05). On weekend days, boys who consumed a poor- or good-quality breakfast spent approximately 6 and 5min less time respectively being sedentary during the mornings compared with breakfast nonconsumers (P,0?05). Boys who consumed a good-quality breakfast spent almost 3min more in MVPA during the morning on weekend days compared with nonconsumers, and boys who consumed a poor- or good-quality breakfast were 22% and 16% more active overall respectively than breakfast non-consumers (P,0?05). During the rest of the day, boys who consumed a good-quality breakfast spent about 11 min less time being sedentary (P,0?05) and 7minmore time in MVPA (P,0?01). CONCLUSIONS Although some associations between breakfast consumption and physical activity were detected for boys, the present study does not provide strong evidence that failing to consume breakfast, or having a low energy intake at breakfast time, is detrimental to children’s physical activity levels.