Inspired by the famous Libby Zion case in 1984, which revealed the underlying flaw in the medical system at the time──the exploitation of junior medical staff and the inadequate surveillanceby attending physicians, authors of this systemic review aim to investigate the potential consequence of overworking in medical scenarios. Methods Excerpta medica database (EMBASE) and PubMed had been systematically searched, bibliographies of relevant studies additionally reviewed. Four cohorts and three randomized controlled trials were selected and quality-assessed with Newcastle-Ottawa Scale and the Cochrane risk of bias tool, respectively. Literature were extracted and discussed. Results Two randomized controlled trials have concluded that residents or interns with longer consecutive working hours per shift in the division of internal medicineare prone to more medical errors. One cohort study has shown a significant association between longer weekly working hours and worsened quality of patient care (intensive care unit (ICU) transfer rates and in-hospital mortality) in the setting of internal medicine. However, none of the 3 studies which were conducted in surgical departments suggests a further restriction on weekly working hours or shift length. Conclusion The specialty-specific policy is recommended based on our between-study comparison. Specifically, with respect to the incidence of medical errors or adverse events, weekly hours or shift length are weakly recommended to be regulated in the department of internal medicine, but there is no recommendation to surgical departments. However, one must consider all respects of the impact brought by any alternation of working policy before the actual implementation.