A systematic review of in-hospital adverse events (AEs) found that approximately 9.2% of hospitalized patients experience AEs, with 43.5% of these events being preventable. Most AEs (56.3%) result in no or minor disability, while 7.4% are lethal. Operation-related (39.6%) and medication-related (15.1%) events are the most common types. AEs are most frequently associated with surgical providers (58.4%) and occur primarily in hospital settings (80.8%). The majority of AEs are found in operating rooms (41.0%) or patient rooms (24.5%). Evidence-based interventions targeting operation- and medication-related events are recommended to reduce AEs. The review highlights the need for improved patient safety measures, as a significant portion of AEs are preventable. However, methodological differences between studies and the limitations of retrospective record reviews may affect the accuracy of the findings. The study emphasizes the importance of focusing on preventable AEs and implementing interventions to improve patient safety.A systematic review of in-hospital adverse events (AEs) found that approximately 9.2% of hospitalized patients experience AEs, with 43.5% of these events being preventable. Most AEs (56.3%) result in no or minor disability, while 7.4% are lethal. Operation-related (39.6%) and medication-related (15.1%) events are the most common types. AEs are most frequently associated with surgical providers (58.4%) and occur primarily in hospital settings (80.8%). The majority of AEs are found in operating rooms (41.0%) or patient rooms (24.5%). Evidence-based interventions targeting operation- and medication-related events are recommended to reduce AEs. The review highlights the need for improved patient safety measures, as a significant portion of AEs are preventable. However, methodological differences between studies and the limitations of retrospective record reviews may affect the accuracy of the findings. The study emphasizes the importance of focusing on preventable AEs and implementing interventions to improve patient safety.