The commercialisation of schools is a controversial issue, but very little is known about the actual situation in UK schools. The aim of this study was to investigate, with particular reference to health education and health promotion, commercial activities and their regulation in primary schools in the Yorkshire and Humber region of the UK. A questionnaire was sent to a random sample of 650 headteachers with respondents being asked whether a range of commercial activities had been present in their school during the previous 20 months. They also indicated whether the school had any policies on the types of activity covered by the questionnaire. The results showed that four types of commercial activity had been present in over 50% of responding schools. These were voucher/token collection schemes, business linked competitions/contests, business linked sports coaching and sponsorship. Voucher/token collection schemes were found to be the most common form of activity, with 85% of schools having participated in at least one of these initiatives. Only 4% of schools had any policies on the types of activity covered in the questionnaire. Further research in the UK on commercial activities in schools is recommended. (Contains 4 tables and 3 figures.)