SUMMARYThis is a review of the clinical studies performed so far in The Netherlands of the treatment of psoriasis with cyclosporin A (CyA), a selective immunosuppressive drug that has caused a major breakthrough in transplant medicine. Data derived from a double‐blind placebocontrolled study (5 mg/kg/day of CyA), dose‐finding studies (2.5 mg vs 5 mg/kg/day and 1 mg, 2 mg or 3 mg/kg/day), and long‐term treatment of chronic plaque‐type psoriasis (1.1–7.2 mg/kg/day) suggest an initial starting dose of 3 mg/kg/day irrespective of the severity of the disease. Long‐term treatment brought about dose‐ and time‐dependent (reversible) side effects, including renal dysfunction and hypertension. Efforts to reduce the dose included concomitant administration of drugs known to have anti‐psoriatic efficacy. Only combination with topical steroids appeared to add to the clinical efficacy of CyA, but did not allow a dose reduction sufficient to restore renal function. Dose reduction through intermittent treatment, however, postponed exacerbations sufficiently to permit at least partial normalization of serum creatinine levels. A similar effect was seen in the treatment of pustular palmoplantar psoriasis, which responded to doses of