The design process involves investigating the current situation to define a design problem, to propose an intervention in form of a solution and to evaluate whether it is satisfactory (Lawson, 2006). Schön (1983) investigates the design practice epistemology as a process of reflection in action. In this context, we explore case-based reasoning concepts (Kolodner e Leake, 1996) to index and recover HCI design cases. An HCI design case can be understood as an HCI problem and solution definition recorded in representations and models during the design activity. Schön (1983) argues that a designer can enrich his reflection in action process when he/she identifies similarities and differences between the current case and other cases he/she already knows. This thesis presents the results of a qualitative research study about the effects of consulting design cases in the reflection in action process of undergraduate and graduate Computer Science students during HCI design activities. In particular, we consider a base of cases with contributions of third parties, that is, those who consulted the cases did not participate in the definition of the problem nor of the solution. In the observed sessions, consulting existing design cases enriches the participants’ reflection in action process through conversation with design artifacts. This result extends Schön’s result considering the consultation of several design cases experienced by third parties. Furthermore, we realized that differences and similarities between the proposed HCI solutions and those consulted depend on the participants’ judgment on the consulted design cases. This judgment may vary at different moments of a design process conducted by the same person.