Epidemics and pandemics are frequently occurring disasters that significantly affect physical and mental health. Their impact also adversely influences the social and financial aspects of life. The effects of an epidemic or pandemic can be direct, wherein individuals are affected by the infection, and the biological changes occurring in the body contribute to psychological symptoms. Conversely, indirect effects are mediated by isolation, quarantine, fear of contracting or transmitting the infection, fear of losing loved ones and lifestyle restrictions related to lockdowns. The recent COVID-19 pandemic is one of the most devastating pandemics of the century, significantly impinging upon both physical and psychological well-being. This chapter discusses the mental health aspects of epidemics and pandemics, with specific reference to the recent COVID-19 pandemic.