We determined the average medical and indirect costs of rheumatoid arthritis (RA) from clinical and community based samples and compared those costs to those experienced by similar persons without RA. We reviewed the literature and analyzed the UCSF RA Panel Study and the National Health Interview Survey for the years 1989-91. The annual medical care costs of RA ranged from $4,300 to $5,700 in 1994 terms in the clinical samples, with hospital admissions accounting for half to two-thirds of the total. Indirect costs in the clinical samples exceeded direct costs and ranged from just under $10,000 to more than $16,000 a year. Medical care costs of RA are highly skewed, with persons in the 90th percentile experiencing costs more than 100 times as large as those in the 10th. In the national community based sample, the costs of RA amounted to $8.74 billion, of which more than half was due to medical care. In this sample, the increment of costs experienced by persons with RA compared to those without was $3.07 billion, with 80% of the excess the result of indirect costs due to wage losses.