Cyclosporine for microemulsion has been widely used in the treatment of rheumatoid arthritis (RA) with remarkably good results over progression of joint damage, as reported by the GRISAR Study. A local group in Argentina, performed a prospective, open label study (Neo-Ra-02), consisting of 12 centres which recruited 50 RA patients, who were followed during 6 months in order to assess efficacy, tolerability and safety of cyclosporine microemulsion in the treatment of RA. Efficacy parameters were: morning stiffness, functional evaluation (HAQ, Lee and Ritchie index) and laboratory and radiological (Larsen score) assessments. Safety parameters were: blood pressure and renal, liver and hematological laboratory data. Patients criteria for participation were: presence of active RA (as defined by the ACR), Steinbrocker anatomic and functional grade I to III, disease evolution no longer than 5 years, no previous history of hypertension, renal or liver disease and absence of DMARDs use during the previous 2 months. There was a statistically significant decrease in morning stiffness and in pain evolution. Improvement became evident after 4 weeks of treatment. Reduction of Ritchie index was significant also at 4 weeks and the same observation was made with tenderness and swollen joint scores. Regarding evolution of CRP and RF, a statistically significant reduction was observed only in positive RF. Safety parameters showed no significant increase in serum creatinine or uric acid: 6/50 patients developed mild hypertension with only a significant increase in systolic blood pressure in comparison with baseline. Cyclosporine microemulsion demonstrated efficacy with minimal adverse events (12% mild hypertension) when appropriately monitored and administered in low doses (3 mg/kg/day).