Many patients with atopic dermatitis are dissatisfied with conventional treatments based on topical steroids and have experienced some traditional remedies and alternative therapies. However, most of such therapies have not been evaluated scientifically and clinically by specialists. This study was designed to assess whether a certain vegetarian diet might be effective for atopic dermatitis and if so, to identify the mechanisms of this remedy through analyses of immunological parameters. An open-trial study was carried out in twenty patients with atopic dermatitis. An improvement of dermatitis was evaluated by SCORAD index and serological and immunological parameters were monitored. After a two-month treatment, the severity of dermatitis was strikingly inhibited, as assessed by SCORAD index and serological parameters including LDH5 activity and a number of peripheral eosinophils. A sharp reduction in eosinophils and neutrophils was observed prior to improvement in the skin inflammation. In addition, PGE2 production by peripheral blood mononuclear cells was reduced by this treatment. In contrast, serum IgE levels did not change during the same period. Although this study is an open-trial one, it suggests that this treatment may be useful for the treatment of adult patients with severe atopic dermatitis.