Objective :Performing a usability study on two handheld computers (personal digital assistant and tablet PC), as tools for retrieving drug information.Materials and methods: A randomised crossover study was performed: 34 students in pharmacy and medicine used the two handheld tools in a randomised order, to answer a questionnaire containing 12 questions covering all the aspects of a drug database and a qualitative analysis on six different items to measure access to drug information. The availability of the drug information database Vidal on PDA and on tablet PC implied our choice of the database. Three main criteria for evaluation were chosen: success rates, time-on-task, and number of clicks.Results: There were no significant differences between the two groups neither on age, sex, medical discipline, study years nor previous computer practice. The success rate is significantly higher with the PDA for only one question. The PDA is significantly faster than the tablet PC on 7 of the 12 questions and generates fewer clicks for 3 questions. Compared to the tablet PC, it appears that the PDA is better in terms of clearness, navigability and usefulness for professional practice and it is the only tool which is significantly preferred to all other supports.Conclusion: In this study with students, the PDA is significantly more effective quantitatively and qualitatively than the tablet PC to retrieve drug information.