Background and Objective: COVID-19 is a fast-spreading worldwide pandemic caused by SARS-CoV-2. The World Health Organization recommended wearing face masks. Masks have become an urgent necessity throughout the pandemic, the study's goal was to track the impact of wearing masks on immunological responses. Materials and Methods: This study was conducted on 40 healthy people who were working in health care at Nineveh Governorate Hospitals from September-December, 2020. They wore face masks at work for more than 8 months for an average of 6 hrs a day. The control sample included 40 healthy individuals, who wore masks for very short periods. All samples underwent immunological and physiological tests to research the effects of wearing masks for extended periods within these parameters. Results: The results showed a significant decrease in total White Blood Count and the absolute number of neutrophils, lymphocytes, monocytes and phagocytic activity. However, there was a significant increase in the absolute number of eosinophils in participants compared with the control. The results also suggested there were no significant differences in IgE, haemoglobin concentration and blood O 2 saturation in participants who wore masks for more than 6 hrs compared to the control group. The results showed a significant increase in pulse rate in participants who wore masks for more than 6 hrs compared to the control group. The results also showed a strong correlation coefficient between the time of wearing masks and some immunological, haematological parameters. Conclusion: Wearing masks for long periods alters immunological parameters that initiate the immune response, making the body weaker in its resistance to infectious agents.