Objective: The objective of this study was to determine knowledge of food hygiene amongst young children (5-7 years), and facilitators and barriers to application of knowledge. Few studies exist that explore the knowledge and attitudes of young children towards food hygiene. This is an important age group, as it is a time when attitudes and behaviours are developing, which may then be carried through to adulthood. Design: To determine knowledge, age-appropriate activities were designed, with teachers, based on expected learning outcomes for this age group. In-depth interviews were carried out to determine attitudes towards and barriers to observing hygienic practices. Setting: Infant schools were selected across the United Kingdom, differing in number of children registered, level of deprivation of location, attainment and proportion of children from ethnic minorities. Methods: Activities were completed in 21 schools by 732 children (5-7 years). Interviews were conducted with 30 children. Findings: Children were generally well informed about handwashing occasions and good practice when preparing foods. They did not, however, always wash their hands when they knew they should, and some misconceptions were established at a young age. Children who understood the reasons for good practices, and who benefited from good facilities, were more likely to perform desired hygiene-related behaviours. The need for a collaborative approach between educators, health promotion professionals and parents was emphasized. (Contains 4 tables.)