The world has been under the negative effect of the COVID-19 pandemic for the last few months. While people may take many preventive behaviours to minimize the risk, very little is known about the factors that can increase preventive behaviours during the COVID-19 pandemic. This study examined the effects of vulnerability, perceived risk, and fear on preventive behaviours of COVID-19. The study used a sample of 4,536 Turkish adults (M = 30.33 +/- 10.95 years) recruited from 17 March through 1 April 2020. Vulnerability, perceived risk, fear, and preventive behaviours were measured with self-rating scales. Participants mostly engaged in avoidance of public transportation and frequent handwashing as preventive behaviours. Women had a significantly higher vulnerability to, perceived risk, and fear of new coronavirus compared to men. Correlation results indicated that age, gender, education level, vulnerability, perceived risk, and fear were related to preventive behaviours. Regression results demonstrated that vulnerability, perceived risk, and fear accounted for a significant amount of variance in preventive behaviours over and above the effects of demographic variables. The results suggest that vulnerability, perceived risk, and fear can significantly increase engagement in preventive behaviours during the novel coronavirus pandemic. The results have important implications for research and practice.