When finding a best explanation for observed symptoms a multitude of information has to be integrated and matched against explanations stored in memory. Although assumptions about ongoing memory processes can be derived from the process models, little process data exists that would allow to sufficiently test these assumptions. In order to explore memory processes in diagnostic reasoning, 29 participants were asked to solve a visual reasoning task (the Black Box paradigm) where critical information had to be retrieved from memory. This study focused on differentiating between processes that take place during the encoding and the evaluation of symptom information by comparing eye movement measures (the number of fixation and fixation duration per dwell). Results will be discussed in light of existing theories on sequential diagnostic reasoning. Further, it will be discussed to which extent eye movements can be informative about memory processes underlying sequential diagnostic reasoning.