Aim: To explore how and why mobile instant messaging applications are used by Filipino nurses as part of their work. Methods: Guided by the uses and gratifications theory, in-depth interviews with 20 staff nurses working in 9 hospitals (ie, 4 private and 5 public hospitals) in the Philippines were conducted in July 2015. Interview data were analysed through a phenomenological perspective to thematic analysis. Results: Results show that mobile instant messaging applications such as Facebook Messenger and Viber were mostly used by staff nurses and these were accessed using their own smartphones. Thematic analysis indicates that they were used to meet staff nurses' need for information exchange, socialization, and catharsis. Moreover, user interactions vary depending on members within a chat group. For instance, communication via mobile instant messaging applications are much formal when superiors are included in a chat group. Conclusion: In general, the results show that mobile instant messaging applications are routinely used by Filipino staff nurses not only for clinical purposes (ie, information exchange) but also for non-clinical purposes (ie, socialization and catharsis). This paper ends with several practical and theoretical implications including future research directions.