The aim of the study was to investigate, in vitro, hydrogen sulphide water balneum effect on erythrocyte superoxide dismutase activity in patients with rheumatoid arthritis. Erythrocytes from 29 consecutive patients with rheumatoid arthritis (11 men, 18 women) aged 54 years were obtained. The control group comprised of 30 healthy subjects with a mean age of about 40 years. Patients with rheumatoid arthritis were subdivided into two groups: with active disease (18 patients) and in remission (11 patients), and secondly into patients receiving (21 subjects) and not receiving (8 subjects) non-steroidal anti-inflammatory drugs. For erythrocyte superoxide dismutase activity evaluation, with method of Misra i Fridovich was used. Superoxide dismutase activity was assessed after 5, 10, 15, and 20 minutes erythrocytes incubation with hydrogen sulphide water. The mean baseline erythrocyte superoxide dismutase activity (T0) was in rheumatoid arthritis patients 1589.95+/-208.41 U/gHb and was 1622.12+/-321+/-321.58 U/gHb in the control group (ns). After 5 and 10 minutes of incubation with hydrogen sulphide water T0-T5 i T5-T10 erythrocyte superoxide dismutase activity increased significantly (p<0.05) in rheumatoid arthritis patients. In rheumatoid arthritis patients erythrocyte superoxide dismutase activity was higher and increased significantly when compared with control group. It seems that hydrogen sulphide water balneum produces an antioxidant effect on erythrocyte status in patients with rheumatoid arthritis.