Rheumatoid arthritis is an autoimmune disease, while osteoarthritis is presumed to be a disease due to wear and tear causing damage to joints. Some environmental exposures, such as smoking, air pollution and possibly persistent organic pollutants, are known to increase the risk of both. We have utilized the National Health and Nutrition Examination Survey (NHANES) data to determine associations between self-reported prevalence of any form of arthritis, rheumatoid and osteoarthritis and various polychlorinated biphenyl (PCB) congeners, several chlorinated pesticides and 2.3,7,8-tetrachloro-dibenzo-dioxin (TCDD). We find that there is a statistically significant association between serum PCB levels of more highly chlorinated PCB congeners and both types of arthritis. The associations are stronger with rheumatoid arthritis than with osteoarthritis, and stronger in women than in men.