Augmentative and alternative communication (AAC) systems can be mounted on a range of different hardware platforms, from custom-designed units to desktop or laptop personal computers and hand-held and palmtop systems. Palmtop devices such as personal data assistants (PDAs) offer great advantages of portability. The small display size and limited storage and processing capacity of a PDA compared to larger systems are likely to impose some limitations on the range of AAC applications which can be supported, however, particularly when multimedia-based applications are considered. This paper addresses issues involved in migrating a multimedia AAC application onto a palm-top PDA and discusses the user involvement in the re-engineering of the system for that environment. Outcomes from an initial practical trial with a person who uses AAC are reported.