It has been recently shown that soluble interleukin-2 receptor (sIL-2R) is related to the pathogenesis of autoimmune diseases. We determined serum levels of sIL-2R in patients with rheumatoid arthritis (RA). Fifty-three patients (3 males and 50 females from 35 to 70 years old) and sex- and age-matched 50 healthy subjects were included in this study. The sIL-2R concentrations positively correlated with Lansbury index of RA (r = 0.602, p < 0.01). There was a significant correlation between sIL-2R levels and the prevalence of CD3+.HLA-DR+ lymphocytes (r = 0.420, p < 0.01).