OKT4:OKT8 ratios of circulating T cells and in vitro suppressor cell function of patients with juvenile rheumatoid arthritis (JRA) were studied and correlations were made with clinical characteristics and laboratory variables of disease activity. Suppression of pokeweed mitogen induced immunoglobulin synthesis by OKT4+ and OKT8+ cells was taken as a measure of suppressor cell function. Mean values of OKT4:OKT8 ratios were increased in patients with JRA. A decrease in suppressor cell function correlated with high OKT4:OKT8 ratios but neither abnormality was related to increased disease activity.