Software maintenance is an activity that requires lots of knowledge. For example, maintainers must know what changes should do to the software, where to do those changes and how those changes can affect other modules of the system. Frequently they do not have enough knowledge to make the best decision and must consult other information sources, but these sources are often unknown or difficult to locate. Therefore, knowledge management could be useful to address some of these problems; however, before knowledge management tools could be developed for software maintenance groups, some questions must be answered: such as what kinds of problems could be solved. In this paper a qualitative approach to the identification of knowledge management needs in software maintenance teams is presented. This approach has been applied in two case studies, and an agent-based knowledge management tool has been designed and implemented from the results obtained.