Medication reviews (MR) are essential for optimizing patient care and drug therapy safety. This study examined clinical pharmacists’ decision-making during MRs. Five clinical pharmacists from university hospitals in Germany conducted intermediate MRs utilizing the think-aloud method, which were transcribed and modeled as knowledge graphs representing their decision-making processes. Our findings revealed variability in decision paths and problem identification, despite pharmacists often reaching similar conclusions. The use of knowledge graphs provided valuable insights into the diverse approaches taken during MR and highlighted challenges in standardizing the process. Further research should refine graph models to capture implicit knowledge and standardize labeling.