Handheld technology had been used in fast food industry in order to improve their customer services. The usability of these handheld systems is important so that waiter can take customer order effectively, efficiently and satisfactorily. This paper describes how a group of undergraduate students took part in designing and developing a PDA food ordering system. All steps taken are documented in this paper. Finally, the advantages of interaction design approach in this case study are presented. Keywords -interaction design, usability, pda food ordering system, handheld technology, fast-food restaurantI.