The prevalence of hip osteoarthritis and rheumatoid arthritis has been found to be lower in Chinese, Japanese, and other Asian populations than in whites. The low prevalence of osteoarthritis hip in the Chinese and Japanese populations cannot be explained by the rarity of hip dysplasia, which is as prevalent in those two populations as in whites. As in other populations, rheumatoid arthritis in the Chinese is associated with the shared epitope of the third hypervariable region of the DR gene. However, the low prevalence of rheumatoid arthritis in the Chinese cannot be accounted for entirely by genetic factors.