OBJECTIVE: To estimate the prevalence of osteoarthritis (OA) and rheumatoid arthritis (RA) in Korean. METHODS: Those who participated arthritis/allergy field study in Icheon, Kyunggi Province and Goesan, Chungbuk Province in 2001 were evaluated for the prevalence of arthritis. Diagnosis of OA and RA were made using American College of Rheumatology criteria. RESULTS: Among the 983 participants (mean age+/-SD, 49.9?14.0 years), 498 participants were male (mean age 49.9+/-13.1 years) and 485 participants were female (mean age 49.9+/-15.0 years), and there was no difference of mean age between male and female. There were 153 cases of OA (15.6%, mean age, 61.6+/-9.5), which consisted of 44 male cases (mean age, 58.9+/-10.7) and 109 female cases (mean age, 62.7+/-9.5). Prevalence of OA was significantly higher in female compared to male (22.5% vs 8.8%, p<0.0001). Prevalence of OA in the 4th to the 8th decade was 1.1, 7.5, 19.4, 34, 37.2%, respectively and showed increasing trend in the ascending order of age in decade (p<0.001). Localization of OA was knees (77.1%), knees and hands (17.6%), and hands (5.2%). RA was detected in 14 cases (1.4%, mean age, 58.8+/-14.6, male to female 1:13). Prevalence of RA was significantly higher in female compared to male (2.7% vs 0.2%, p<0.01). CONCLUSION: The prevalence of knee or hand OA and RA were 15.6% and 1.4% in Korean, respectively. The prevalence of OA was significantly higher in female and aged individuals. The prevalence of RA was also significantly higher in female.