OBJECTIVE: The predominance of marketing of products high in fat, sugar and/or salt to children has been well documented and implicated in the incidence of obesity. The present study aimed to determine whether foods marketed to children in UK supermarkets are nutritionally similar to the non-children's equivalent, focusing on food categories that may be viewed as healthier options. DESIGN: Nutritional data were collected on yoghurts (n 147), cereal bars (n 145) and ready meals (n 144) from seven major UK supermarkets and categorised as children's or non-children's products based on the characteristics, promotional nature or information on the product packaging. Fat, sugar and salt content was compared per 100 g and per recommended portion size. SETTING: UK. RESULTS: Per 100 g, children's yoghurts and cereal bars were higher in total sugars, fat and saturated fat than the non-children's; this was significant for all except sugar and total fat in cereal bars. Per portion these differences remained, except for sugars in yoghurts. Conversely children's ready meals were significantly lower in these nutrients per portion than non-children's, but not when expressed per 100 g. Children's yoghurts and ready meals had significantly lower sodium content than non-children's both per portion and per 100 g. CONCLUSIONS: Significant differences between the nutritional composition of children's and non-children's products were observed but varied depending on the unit reference. A significant number of products marketed towards children were higher in fat, sugar and salt than those marketed to the general population.