en عمومى General پژوهشي Original article <strong>Background</strong>: COVID-19, which began in December 2019 in China, can have a broader impact on individuals&#39; mental dimensions. Meanwhile, the medical staff battling this epidemic are more at risk of mental and emotional problems.&nbsp; This study aimed to examine the level of stress, anxiety, and depression and their relationship with the level of knowledge of medical staff battling in COVID-19 pandemic treatment.<br> <strong>Methods:</strong> This descriptive-analytical study was conducted on 641 medical staff using an online platform to design the questionnaire, and its link was placed in different groups of social networks all over the country&nbsp; in which the medical staff battling COVID 19 were members. Statistical analysis was performed by SPSS ₂₅and Kolmogorov-Smirnov test, independent samples t-test, independent one-way analysis of variance, and chi-square.<br> <strong>Results</strong>: Higher knowledge about COVID-19 was associated with younger age, clinicians, and nurses. Moreover, females were more knowledgeable in terms of support; while males were more reliable in washing hands and disinfecting wet places. Based on the categorical version of psychological factors, the majority of cases had severe stress ( 39.80 % ), normal depression ( 48.50 % ), and normal anxiety ( 57.30 % ). Finally, it was found that married participants had more knowledge about COVID-19, but knew less about its fatality.<br> <strong>Conclusion</strong>: Studies have shown negative psychological experiences caused by COVID-19 in nurses, including negative emotions, such as fatigue, discomfort, helplessness due to high-intensity work, anxiety, and worry about family members. COVID-19, Stress, Anxiety, Depression, Treatment staff 234 243 http://jebhpme.ssu.ac.ir/browse.php?a_code=A-10-310-1&slc_lang=en&sid=1 Hossein Bahrami Moghadam 0000-0002-5863-0182 No Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Reza Khedri 0000-0002-4532-336X No Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Arash Forouzan 0000-0003-0754-9779 No Department of Emergency Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Mahmood Maniati 0000-0002-6832-1615 No Department of English, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Payam Amini 0000-0001-8675-0045 No Department of Biostatistics and Epidemiology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Ali Delirrooyfard adelir2891@gmail.com 0000-0002-9438-2665 Yes Clinical Research Development Unit, Imam Khomeini Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Hossein Eisvand 0000-0002-0509-3491 No Student Research Committee, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Mehdi Sayyah Bargard 0000-0003-2023-9521 No Education Development Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran Mina Jaberi 0000-0003-0248-5606 No Clinical Research Development Unit, Golestan Hospital, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran