BACKGROUND AND OBJECTIVES: Numerous studies have been conducted on the psychological effects of the COVID-19 pandemic. However, how the mental health of health workers will be affected among the number of peaks during the pandemic has not been evaluated yet. The study aims to investigate the effects of the fi rst, second, and third peaks of COVID-19 on anxiety, depression, and stress symptoms in healthcare workers. METHODS: The current study included 4031 healthcare workers, 1051 during the fi rst peak period, 1409 during the second peak period, and 1571 during the third peak period. The Depression-anxiety-stress scale-21(DASS-21) was used to assess the participants' levels of anxiety, depression, and stress symptoms. RESULTS: The mean age of the participants was 33.74 ± 7.95, and 2634 (66.3 %) were female. 36.9 %(n = 1486) of the participants were physicians, 41.1 % (n = 1655) were nurses and 22.1 % (n = 890) were other healthcare workers. A statistically signifi cant difference was documented in the DASS-21 anxiety (F (2:4028) = 502.893, p < 0.001, Post-hoc = 3.