Objective. To determine whether there is a secular decline in the incidence of rheumatoid arthritis (RA), as has been suggested by previous studies.

Methods. In the absence of comprehensive data in the United States population, we estimated RA incidence in a health maintenance organization population from 1987 through 1990 and compared the rates with those in an earlier, similarly performed study from Rochester, Minnesota, which covered the years 1950 through 1974. RA estimates were based on our review of medical records of patients who had been diagnosed as having RA or related diseases during the period of January 1, 1987 through December 31, 1990.

Results. Annual age-standardized incidence of classic or definite RA (according to the American College of Rheumatology [formerly, the American Rheumatism Association] 1958 criteria) in patients aged 18 or older was 22 per 100,000 in men and 60 per 100,000 in women. The incidence of RA increased with age, with a marked increase in women older than 50.

Conclusion. We found no secular change in RA incidence compared with the similarly ascertained historical data.