Background: Nursing burnout is affected by various factors, including work overload. Since the inauguration of the Health Sector Evolution Plan (HSEP) in Iran in 2014, government hospitals have been required to provide health services to the public at all levels. This decision, however, has increased the volume of patients admitted to government hospitals. Because nurses are on the front line of health services, they are faced with a greater load of care provision. Purpose: This study aimed to evaluate nursing burnout before and after HSEP in Iran, with an emphasis on the differences between government and private hospitals. Method: This retrospective panel study used Maslach’s burnout inventory to evaluate nursing burnout in 371 nurses working in government and private hospitals in Shiraz, Iran, before and 7months after the health sector reform. Chi-square test and paired t test were used to compare burnout scores. Results: The results showed that nursing burnout had changed significantly after HSEP was launched (p = .030). A more detailed assessment found that burnout and emotional exhaustion had both increased significantly in the government-hospital group (ps = .014 and .001, respectively). However, no significant change in burnout was found in the private-hospital group over the same period. Conclusions/Implications for Practice: The findings of this study indicate an increase in nursing burnout in government hospitals. An important issue in every health sector reform is nursing resource management, with a focus on burnout. Accordingly, policymakers should consider the work overload situation of nurses and work to prevent increased burnout, especially emotional exhaustion.