The present study was conducted to examine the developmental patterning of food preferences in a large sample of British schoolchildren and to investigate possible gender differences. Using a cross-sectional survey design, the study was carried out in three primary and three secondary schools in West London, UK. A total of 1291 children aged from 4 to 16 years completed a 115-item food preference questionnaire in class time, supervised by class teachers and assistants. Children indicated whether they had ever tried each item and, if so, how much they liked it. We observed age-related increases in the number of foods tried (P<0·001), liked (P<0·005) and disliked (P<0·05). Controlling for the number of foods tried rendered the increase in dislikes non-significant and reversed the age effect on the number liked. Girls liked fruit (P<0·05) and vegetables (P<0·001) more than boys did; boys liked fatty and sugary foods (P<0·005), meat (P<0·001), processed meat products (P<0·001) and eggs (P<0·05) more than girls did. Some age differences were apparent in liking for categories of food, although the effects were not linear. Across ages and genders, children rated fatty and sugary foods most highly, although ratings for fruit were also high. Children's food preferences overall are not consistent with a healthy diet. Interventions should focus on increasing the familiarity, availability and accessibility of healthy foods and should be mindful of the need to target messages appropriately for boys who have less healthful food preferences than girls at all ages.