Objective: In the UK there have been no initiatives identified to increase the use of sun safety policies in preschool establishments. This study tests the hypothesis that health visitors with appropriate sun safety training can successfully facilitate the development and implementation of sun safety policies and practices in preschool education and care establishments. Design: A two-stage randomised controlled study. Setting: All providers of preschool care or education situated within the boundaries of North Derbyshire Health Authority (n = 198). Method: In stage one an initial postal screening survey of all preschool providers was conducted to determine the extent to which their policies and practices were consistent with ideal practice for sun safety. Providers who did not have a written sun safety policy were invited to participate in stage two of the study in which they were randomly assigned to either intervention group or control group. The intervention establishments received visits over a four-month period from a health visitor who had attended a one-day sun safety training event. Results: The overall response rate to the initial screening survey was 67 per cent (n = 133) of which 90 per cent did not have a written sun safety policy (n = 96). In the intervention group (n = 33) 88 per cent (n = 29) of playgroups and nurseries had changed their sun safety practice by developing and implementing a sun safety policy, following visits from a health visitor. For example, the percentage of children wearing sun hats was associated with policy development (r = 0.4, p less than 0.05). In the control group (n = 41) no changes had been made to sun safety policy or practice. Conclusion: This is an important finding for Primary Care Trusts who are charged with the development of the public health capacity of health visitors. (Contains 3 tables and 1 figure.)