Objective Parents are exposed to many different information sources about children's medicines, including recommendations from other people, the media, and their own previous experience. The aim of this paper is to explore the influence of different information sources upon their non-prescription medicine purchases for children aged 0-4 years. Setting The setting was thirty-nine community pharmacies across four Primary Care Trusts in England. Main outcome measure We explored the type and range of information sources used by parents in purchasing non-prescription medicines. Methods A self-completion survey and a subset of semi-structured telephone interviews were undertaken with parents/carers buying oral medicines for children aged 0-4 years. Results One hundred and thirty-four surveys and thirty-eight interviews were completed: most participants were 25-44 year-old women. Recommendations from other people, both from health professionals and family members, were most often cited as influencing parents' and carers' choice of medicine. Advertising, and well-known brands of children's medicines, were also influential. The Internet and other media were less often cited as sources. Medicines leaflets and packaging were found to be useful: a significant minority admitted difficulty in understanding all the information therein. Conclusion This study explored the information sources reported at the point of a specific medicine purchase, thus reflecting actual behaviour rather than general perceptions of useful sources. Parents and carers of preschool children reported a number of professional and lay influences on their medicine purchase choices. Pharmacists and staff should consider these influences when advising children's medicine purchasers. A combination of spoken advice and written reminder information would meet the preferences of most purchasers.