Oral and dental diseases may be associated with other chronic diseases. Using data from the National Health and Nutrition Examination Survey 1999-2004, the authors calculated the prevalence of untreated dental diseases, self-reported poor oral health and the number of missing teeth for adults in the United States who had certain chronic diseases. The authors used multivariate analysis to determine whether these diseases were associated with indicators of dental disease after controlling for common risk factors. Participants with rheumatoid arthritis, diabetes or a liver condition were twice as likely to have an urgent need for dental treatment as were participants who did not have these diseases. After controlling for common risk factors, the authors found that arthritis, cardiovascular disease, diabetes, emphysema, hepatitis C virus, obesity and stroke still were associated with dental disease. The authors found a high burden of unmet dental care needs among participants with chronic diseases. This association held in the multivariate analysis, suggesting that some chronic diseases may increase the risk of developing dental disease, decrease utilization of dental care or both. Dental and medical care providers should work together to ensure that adults with chronic diseases receive regular dental care.