Background: Due to the chronic nature of atopic dermatitis and dependence of most patients to steroids, finding a suitable alternative treatment is important. Objectives: To determine the efficacy of phototherapy in treatment of atopic dermatitis, also to evaluate possible influencing factors in response of patients to psoralen+UVA (PUVA) therapy. Patients and Methods: 13 patients with resistant atopic dermatitis, older than 10 years, were treated with PUVA, 2 or 3 times a week until complete recovery or maximum of 30 sessions. Rate of recovery was determined according to reduction in 6 signs including itching, erythema, lichenification, xerosis, exfoliation and excoriation at the end of the treatment period and 2 months later. Results: 10 patients (77%) at the end of the treatment and 9 patients (69.2%) two months after that, showed more than 50% recovery. There was no significant relationship between the pretreatment serum IgE levels, site of the lesions, age, sex and phototherapy. The patients with family history of atopic dermatitis showed a better response to the treatment. Conclusion: PUVA is a suitable alternative treatment in resistant cases of atopic dermatitis.