BACKGROUND: WhatsApp is an instant messaging application that has grown in popularity over the last decade. The literature has focused on the use of WhatsApp in medical, surgical and nursing disciplines, with little work exploring pharmacists' experiences of using WhatsApp to provide services. OBJECTIVE(S): The aim of this research was to explore pharmacists' experiences of using WhatsApp to support delivery of out-of-hours pharmacy services. METHODS: A qualitative design was underpinned by a phenomenological philosophy. Focus groups and an extract of the WhatsApp transcript were thematically analysed using NVivo. RESULTS: Over three hundred communication events (1580 messages) were analysed in the WhatsApp transcript. Message type was classified as follows; handover (26%, n = 410), procedural queries (26%, n = 410), laptop location (18%, n = 284), whole staff communication (24%, n = 379), clinical queries (5%, n = 79), and administrative communications (1%, n = 16). A total of five focus groups were conducted between October and November 2017 with 27 participants that included pharmacists with different levels of experience. The findings suggest that WhatsApp improved communication between junior and senior pharmacists, particularly during the global cyber crisis, and provided an opportunity to share best practice. Concerns were raised regarding the encroachment of work activities into personal time. Additionally, the tacit approval by senior pharmacists to group information sharing and solution development, despite the potential for non-active participation, highlighted the issue of collective complicity. CONCLUSIONS: WhatsApp can be a useful platform to support the delivery of out-of-hours services through professional development, improving communication and supporting relationships. This paper demonstrates that service managers must consider multiple ethico-legal and social frameworks when developing or allowing the organic development of such communication methods within healthcare provider organisations.