The role of increased plasma prolactin (PRL) in rheumatoid arthritis (RA) is not fully explained. The aim of this study was to compare the clinical features and the treatment administered in RA patients with normal and elevated plasma PRL concentrations. Forty-nine patients with rheumatoid arthritis and 16 healthy subjects were included in this study In healthy controls, PRL concentrations were 7.6 micro/l (median), in 34 patients plasma PRL was less than 20 micro/l (9.9 micro/l) and in 15 patients it was elevated, with a median of 26.7 micro/l. No differences in clinical features were found compared with normal or increased plasma PRL. The introduction of corticoid therapy produced a significant difference. Steroid therapy was administered to 93% of the patients with hyperprolactinemia, compared with 59% of those with normal PRL concentrations. Daily prednisone doses higher than 5 mg were administered to 43% of the patients with elevated PRL, compared with 25% of patients with normal prolactin concentrations. In conclusion, the clinical feature of patients with rheumatoid arthritis did not differ in subjects with elevated PRL concentrations and in those with normal concentrations. The difference between these two groups was in the higher demand for steroid therapy in patients with hyperprolactinemia.