Burnout syndrome is a collection of adverse symptoms that affect nursing staff employed in medical facilities. This syndrome is marked by a low mood, mental fatigue, and physical discomfort. Its emergence is impacted by strenuous work, organizational problems, and interpersonal conflicts. The aim of this study was to analyze the degree of mental burden and occupational burnout of nurses employed in Hospital Emergency Departments (ER). The data collection was based on the author’s questionnaire, as well as the MBI Maslach occupational burnout questionnaire and the Meister’s mental burden assessment questionnaire. The sample comprised 113 professionally active nurses employed in the HED. Conclusions: (1) the respondents exhibit a low and medium level of occupational burnout and mental workload, (2) socio-demographic factors, work experience and prevention methods do not affect the level of mental workload and occupational burnout, (3) employment in several workplaces causes a higher level of workload and professional burnout, (4) satisfaction with remuneration and support from colleagues is a key factor in reducing the risks of professional burnout.