Many existing training programs for Health Information Systems (HIS) do not adequately satisfy end users' needs nor meet training objectives. This is because they do not envisage the problems that users may encounter when performing specific tasks. Therefore the first priority for the development of an effective training program is to precisely assess the end users' training needs, a process called Training Needs Assessment (TNA). Applying traditional approaches for TNA, such as interviews or surveys alone, however, may be insufficient because they are limited in their capacity to reveal the cognitive processes of end users. Usability testing, with its ability to gather data about human computer interaction, overcomes the deficiencies of these traditional approaches. This paper proposes a multi-method approach, which combines usability testing together with traditional methods, such as interviews or questionnaire surveys to assess HIS end users' training needs. This innovative method is able to precisely reveal the training needs for different levels of HIS users. A case study, which applied this method to assess the training needs for users of a nursing information system demonstrates its feasibility.