Purpose: The objective of this study was to identify the factors related to atopic dermatitis and its prevalence among Korean adults, and to examine the relationship of vitamin D levels to AD prevalence. Methods: Combined data from the 2008-2013 Korea National Health and Nutrition Examination Survey were analyzed by using the chi-squared test and multivariable logistic regression. Results: AD prevalence among 27,860 Korean adults was 2.7% and varied significantly with age, body mass index, and vitamin D levels, as well as presence of asthma, depression, and stress. Vitamin D deficiency and insufficiency were found in 66.8% and 27.5%, respectively. Only 5.7% had sufficient vitamin D levels. Age and asthma were factors associated with an increased prevalence of AD in those with vitamin D deficiency (7.57 times and 2.87 times, respectively), and insufficiency (4.42 times and 2.58 times). However, there were no such risk factors in patients with sufficient vitamin D levels. Conclusion: This study showed that patients with higher vitamin D levels have decreased AD prevalence despite risk factors. Development of an intervention program including lifestyle improvement is suggested.