Background: One unprecedented year after the coronavirus disease 2019 (COVID-19), the pandemic is no longer a short-term stressor; the unremitting/chronic effects of COVID-19 disease is likely to cause impaired physical and mental health upon population and the implemented public health and social measures to limit transmission and reduce mortality and morbidity from COVID-19 expose many people to social isolation, job loss, and economic recession. This study aims to compare mental status and four mental symptoms (somatization, anxiety, depression, and social functions) between two periods during the first year of the COVID-19 pandemic. Materials and Methods: Current study consists of two cross-sectional mental health surveys on the Iranian adult population carried out in two periods of March to April 2020 and December 2020 to February 2021 in two important Provinces of Iran (Fars and Khorasan Razavi). In the first survey, 1337 individuals participated in the study and completed the General Health Questionnaire-28, while in the second survey, 1205 participants completed the same questionnaire. Results: Among 1337 participants of the first survey, there were 876 (65.5%) females and 461 (34.5%) males with an average age of 37.41±10.58 years. In the second survey, there were 1205 participants with mean age of 33.79±19.57 years. The rates of females and males were 57.7% and 42.3%, respectively. Compared to the first survey, the second one showed that poor mental health condition that was 1.40 (95% confidence interval: 1.17-1.67) times higher based on the age, sex, education, marital status, economic, alcohol, cigarette, water-pipe, and sedative (P<0.001). Conclusion: Poor mental health status has increased during the first year of the COVID-19 pandemic. These results revealed that the COVID-19 pandemic was a chronic stressor faced by people every day; therefore, more robust mental health-related considerations must be implemented. [GMJ.2021;10:e2199]