During 1981, centers in Phoenix, Saskatoon, Stanford and Wichita monitored hospitalizations for 816 patients with rheumatoid arthritis. Admission rates varied 2-fold, and admissions for evaluation and treatment 10-fold across centers. Admissions were related primarily to disease severity, but in US centers, were reduced by a factor of 3 by prepaid health care. Length of stay was shortest in California (7.3 days), and longest in Saskatoon (16.3) where designated arthritis beds and government prepaid health care existed. Average charges for surgery were as high as $10,000 in Phoenix and as low as $4550 in Wichita. Charges and length of stay were unrelated to disease severity, but were responsive to health care delivery system, availability of facilities, and geographic and center variation.