Memory problems are often associated with the ageing process and are one of the commonest effects of brain injury. Electronic memory aids have been successfully used as a compensatory approach to provide reminders to individuals with prospective memory problems. This paper describes the usability issues surrounding the development of a new memory aid rendered on a personal digital assistant (PDA); in addition, it discusses the importance of a user-centred design process for the development of the memory aid and preliminary qualitative findings from interviews and focus groups of disabled or elderly users.