Atopic dermatitis is one of the most common inflammatory skin diseases among children and adults. Although the risk factors for atopic dermatitis have not yet been fully identified, exposure to mercury may be an important environmental risk factor. The objective of this study was to evaluate the association between mercury body burden and prevalence of atopic dermatitis in an adult population. We recruited participants (n=1990) aged 20 years or older, using stratified random sampling of Korean census blocks. Demographic characteristics and medical history of atopic dermatitis were collected from participants by questionnaire, and mercury levels were determined by an analysis of blood samples. We found that demographic factors such as sex, age, alcohol drinking status, income, and fish or shellfish consumption were important covariates determining blood mercury concentration. Sex and cigarette smoking status were important demographic variables affecting the prevalence of atopic dermatitis. After adjusting for demographic factors, blood mercury concentrations were positively associated with lifetime prevalence of atopic dermatitis [odds ratio (OR), highest vs. lowest tertile=1.50; 95% confidence interval (CI), 1.02-2.21; p for trend=0.057]. This association became stronger for 1-year prevalence of atopic dermatitis (OR, highest vs. lowest tertile=1.82; 95% CI, 1.17-2.83; p for trend=0.026). Mercury body burden and atopic dermatitis prevalence vary across demographic characteristics, and increased blood level of mercury was related to an incidence of atopic dermatitis in this adult population.