We evaluated oral zinc sulphate as a disease-modifying antirheumatic drug (DMARD) in psoriatic arthritis in a preliminary open uncontrolled trial. Twenty patients with psoriatic arthritis were given oral zinc sulphate three times a day at total dose of 600 mg/die, i.e. 120 mg/die of elemental zinc, for 6 months. The 18 patients who completed the trial showed a significant decrease in the number of swollen (p less than 0.01) and tender (p less than 0.05) joints, Ritchie articular index (p less than 0.01), need for nosteroidal anti-inflammatory drugs (p less than 0.001), erythrocyte sedimentation rate (p less than 0.01), and plasma copper level (p less than 0.001). We suggest that zinc sulphate may be an effective and well-tolerated DMARD in psoriatic arthritis. To more strictly verify these preliminary data, a double-blind placebo controlled study is in progress.