In this study, it was aimed to investigate the relationship between Covid-19 fear and intolerance of uncertainty and generalized anxiety disorder in individuals aged 18-65 years and older. Also, it was examined whether Covid-19 and intolerance of uncertainty predicted generalized anxiety disorder significantly. In this study, data were collected from a total of 843 people, including 547 female (64.9%) and 296 male (35.1%) in July and August 2020. In this study, it was used to measure Covid-19 fear that Covid-19 Fear Scale, for the intolerance of uncertainty that The Intolerance of Uncertainty Scale (IUS), for generalized anxiety disorder that General Anxiety Disorder Test (GAD-7). The correlation between COVID-19 fear total score and IUS total score and sub-scales’ scores, and GAD-7 total score was examined using the Pearson Product-Moment Correlation Coefficient technique. As a result of the analysis, it was seen that there were significant and positive relationships between Covid-19 fear total score and IUS total and subscales’ scores and GAD-7. Additionally, the prediction level of COVID-19 fear and intolerance of uncertainty on generalized anxiety disorder was tested with a Multiple Regression Analysis and it was observed that the fear of COVID-19 and IUS total score, IUS1, IUS4 were significant predictors of generalized anxiety disorder.