The aim of this study was to assess the effectiveness of cyclosporine in patients with chronic big plaque psoriasis. Fourteen patients with psoriasis lasting a mean of 16.4 years (13 male, mean age 44.6 years), were treated with 5 mg/kg/day of cyclosporine during a mean of 38.5 days and they were followed after discontinuing the treatment. Patients were assessed weekly using the psoriasis area severity index (PASI), complete blood count, cyclosporine levels and blood chemistry. A remission of the disease was achieved in 12 patients, one did not improve and one had a sprout during treatment. After discontinuing the treatment all patients had gradual relapses of the disease in a period of 0. 5 to 6.5 months. During treatment, serum creatinine increased in 6 patients, serum bilirubin in 7 and alanine aminotransferase in 4. It is concluded that cyclosporine is beneficial in psoriasis but there is a relapse once the treatment is discontinued.