28 patients with stable chronic psoriasis completed a trial in which they were randomly allocated to receive either 10 fish-oil capsules ('MaxEPA') or 10 placebo capsules (olive oil) daily. Patients were specifically instructed not to change their normal diet. After 8 weeks' treatment there was a significant lessening of itching, erythema, and scaling in the active treatment group, with a trend towards an overall decrease in body surface area affected. No change occurred in the placebo group.