We studied whether patients with seropositivity in early rheumatoid arthritis (RA) comprise a different clinical group than those with seronegativity. Four hundred seventeen patients with early RA according to the American College of Rheumatology criteria (disease duration less than 1 year) were retrospectively studied by analysis of demographic, clinical, laboratory, radiological, and therapeutic disease characteristics from the time of diagnosis until the end of the study period (1981 1999) using a data base. There were 248 seropositive patients and 169 seronegative patients with RA. No statistically significant differences were seen between the two groups before commencement of the study period in relation to age of disease onset, male:female ratio, and disease duration. However, seropositive patients showed longer medical follow-up. In addition, at disease onset, seropositive RA patients presented more frequently with symmetrical polyarthritis and small joint involvement than seronegative patients. The seropositive group also had more tender and swollen joints, weaker grip strength, and higher erythrocyte sedimentation and C-reactive protein rates during the follow-up period. In contrast, the seronegative group had less severe radiological findings and greater functional ability at the end of the study. In Greek patients with early RA, rheumatoid factor seems to be a predictor of more severe disease activity.