One common objective of instructional multimedia products is enhancement of learning. It follows that one of the primary tasks of the interface designer is the creation of a user-interface that is motivating, interactive, intuitive and at the same time imposing as minimal as possible a cognitive load on the learner. To achieve this goal, qualities such as learnability, efficiency, memorability, low error rates and high user satisfaction are essential. A well-designed interface should inform the user what do the objects on the screen stand for and what they might do and allows the user to break down a task into subtasks and map them on to the system's functions easily and naturally. By doing so, it enables the user to build a functional mental model of the system that does not require user's rote memorization. These qualities of a well-designed interface are commonly known as the "usability" of software. To date, many methods that allow systematic ways of evaluating usability in instructional multimedia have been developed. By integrating these methods into the various stages within the life cycle of instructional multimedia design and development, the usability of instructional multimedia, and hence its educational value, could be assured. However, there has been little attempt to consolidate these methods into a more integrative and self-explanatory model. This paper attempts to review these various methods under a proposed framework in the hope that it may help readers to select the most appropriate usability evaluation method according to their needs.