Four secondary schools in Southampton were chosen to study the effect of the changes in Social Security regulations in April 1988 on the food intake of schoolchildren. A self-completed questionnaire asking about food intake throughout the previous school day was given to each child by the form teacher on two occasions; one in March 1988 and again after the benefit changes in May 1988. All children who were entitled to a Family Income Supplement (FIS) free school meal in March were included in the study. This group (n = 50) was compared with an age- and sex-matched group of children entitled to a Supplementary Benefit (SB) free school meal (n = 49) and a control group (n = 100) of children. Before the benefit changes there were a few differences between the groups, mainly in the control group, who had different foods at lunchtime. After the benefit changes only 10 per cent of the FIS group had a school lunch compared with 66 per cent before. The major changes were at the lunchtime meal, with fewer in the FIS group eating burgers, pies, chips and ice-cream, and more eating crisps, sandwiches and fruit than had done so before the benefit changes.