Abstract An open-label, uncontrolled, 24-week study was conducted in Hong Kong to determine the most effective regimen and the efficacy, tolerability, and side effects of low-dose cyclosporine therapy in the treatment of patients with psoriasis. Thirty patients were treated with a dosage of 2.5 to 5 mg/kg per day for 16 weeks. At each of the follow-up visits, the modified Psoriasis Area and Severity Index score, blood pressure, and serum creatinine and potassium levels were measured. At the end of 16 weeks of treatment, 77% (23) of the patients had ⩾50% improvement, and 43% (13) had ⩾75% improvement. The mean established dosage was 3 mg/kg per day. The improvement reached a plateau around week 12. Only 7% (2) of the patients had elevated serum creatinine levels (>30% of baseline). Thus low-dose cyclosporine was effective and relatively safe for short-term treatment of patients with severe and refractory psoriasis. However, the relapse rate was high (47%) after cessation of treatment.