Objectives: To apply sociological theories to understand public trust in extended services provided by community pharmacists relative to those provided by general practitioners (GPs). Design: Qualitative study involving focus groups with members of the public. Setting: The West of Scotland. Participants: 26 purposively sampled members of the public were involved in one of five focus groups. The groups were composed to represent known groups of users and non-users of community pharmacy, namely mothers with young children, seniors and men. Results: Trust was seen as being crucial in healthcare settings. Focus group discussions revealed that participants were inclined to draw unfavourable comparisons between pharmacists and GPs. Importantly, participants' trust in GPs was greater than that in pharmacists. Participants considered pharmacists to be primarily involved in medicine supply, and awareness of the pharmacist's extended role was low. Participants were often reluctant to trust pharmacists to deliver unfamiliar services, particularly those perceived to be 'high risk'. Numerous systembased factors were identified, which reinforce patient trust and confidence in GPs, including GP registration and appointment systems, GPs' expert/gatekeeper role and practice environments. Our data indicate that the nature and context of public interactions with GPs fostered familiarity with a specific GP or practice, which allowed interpersonal trust to develop. By contrast, participants' exposure to community pharmacists was limited. Additionally, a good understanding of the GPs' level of training and role promoted confidence. Conclusion: Current UK initiatives, which aim to implement a range of pharmacist-led services, are undermined by lack of public trust. It seems improbable that the public will trust pharmacists to deliver unfamiliar services, which are perceived to be 'high risk', unless health systems change in a way that promotes trust in pharmacists. This may be achieved by increasing the quality and quantity of patient interactions with pharmacists and gaining GP support for extended pharmacy services.