In order to define the effects and safety of cyclosporin A (CsA) in systemic lupus erythematosus (SLE), we conducted an open clinical trial with 16 SLE patients. During an observation period of up to 64 months and an average treatment period of 30.3 months, 16 SLE patients, who did not have adequate disease control or experienced side-effects with their previous immunosuppressive therapy, were treated with CsA (3–5 mg/kg). In 3/16 patients, CsA treatment was discontinued because of side-effects, in two because of inefficacy and in 2/16 because of a pregnancy. Four out of 16 patients had a flare of disease during CsA therapy 7, 24, 36 and 40 months after initial response to therapy; one patient stopped CsA treatment after 54 months of successful disease control. Four out of 16 patients are still on CsA. The best beneficial effect was observed in 10 patients with proteinuria, which decreased from 4.7 ± 2.6 to 1.5 ± 1.1 g/24h. In 3/3 patients with thrombocytopenia and 3/3 patients with leucocytopenia, platelets and leucocytes returned to normal values. The most frequent side-effects were hypertension and deterioration of renal function (3/16) and hypertrichosis (5/16). According to the preliminary results of this study, CsA was well tolerated and able to control disease activity over an extended time period. These data should encourage investigators to perform a multicentre controlled trial on CsA therapy in SLE.