T helper (Th)1 insufficiency was recently found to be related to the pathogenesis of pemphigus vulgaris (PV). Decreased Th1 response was particularly noticed in the early stages of PV. Therefore, administration of interferon alpha in the early stages of aggressive PV may lead to rapid control of the acute stage of the disease. Our aim was to evaluate the role of interferon alpha in the treatment of PV. 30 patients with acute severe PV (>60 % affection) and 30 age and sex-matched healthy subjects were included in this RCT. Patients were randomly divided into two groups (A and B). Group B patients received interferon retard (one subcutaneous injection/week for 4 weeks) in addition to our protocol for the treatment of PV (systemic pulse corticosteroids/cyclophosphamide in combination with sulphasalazine and pentoxifylline) that was administered to all the included patients. IFN-γ and IL-4 were estimated by ELISA before treatment, after 4 weeks and at the end of the study duration (12 weeks). Clinical assessment was done by PAAS on a biweekly basis. All PV patients showed significantly (P < 0.001) elevated levels of IL-4 and significantly (P < 0.001) depressed mean concentration of IFN-γ as compared with healthy controls. Twelve weeks after therapy both groups showed significant improvement in their mean PAAS being more evident and more rapid in group B. IFN-γ was elevated significantly and IL-4 was dropped significantly in group B patients in comparison to group A (P < 0.001). As a conclusion, interferon therapy in severe PV could achieve a more prompt and better clinical response.