This 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 placebo-controlled 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 1.1-6.1 mg/kg/day.