Background& Objective: pemphigus vulgaris is a life threatening relapsing disease, the first line in its treatment is systemic steroids, and due to the high rate of side effects caused by systemic steroids in pemphigus vulgaris patients ,some immunosuppressant drugs have been introduced as an adjuvant steroid sparing agents , and one of these immunosuppressants is azathioprine, which is the most used drug by therapists, but this use was due to experience and not due to strict studies , this research studies the relationship between azathioprine and relapse in pemphigus vulgaris patients during the prednisolone reduction period. Materials & Methods: 70 pemphigus vulgaris patients have been studied, from the patients of the dermatology university hospital during the period between 1/8/2008 -29/5/2011 (the first year for collecting the sample and the rest for follow-up) they have been divided into 2 groups. The first: were treated with prednisolone plus azathioprine (30 patients ), the second : were treated with prednisolone alone (40 patients ).and after the control of the disease the dose of prednisolone was reduced gradually ,till it was stopped, and patients were observed for relapse. Results: there was no meaningful statistical difference between the two groups in the terms of relapse, as giving azathioprine did not reduce the relapse rate, and did not reduce the prednisolone dose needed to prevent relapse. Conclusion: in this study no use of azathioprine in preventing relapse in pemphigus vulgaris patients, so we advise for more studies to confirm that, and to give more attention during its prescription.