The purpose of this study was to investigate whether fish oil and/or corn oil had a beneficial effect on the clinical state of atopic dermatitis, and to evaluate the dietary intake of nutrients in this group of patients. In a double-blind, multicentre study lasting 4 months, during wintertime, 145 patients with moderate to severe atopic dermatitis were randomly assigned to receive either 6 g/day of concentrated n-3 fatty acids, or an isoenergetic amount of corn oil. As local treatment, only an emollient cream or hydrocortisone cream was allowed. The fatty acid pattern in serum phospholipids, and the dietary intake of nutrients were monitored in a subgroup of patients, and the results were compared with a group of patients with psoriasis. The overall clinical score, as evaluated by the physicians, improved during the trial by 30% in the fish oil (P < 0.001) and 24% in the corn oil group (P < 0.001). This was also consistent with the results from a selected skin area, and it was further confirmed by the total subjective clinical score reported by the patients. There were no significant differences in the clinical scores between the two groups at baseline, and at the end of the study. In the fish oil group, the amount of n-3 fatty acids in serum phospholipids was significantly increased at the end of the trial, compared with pretreatment values (P < 0.001), whereas the level of n-6 fatty acids was decreased (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)