BACKGROUND: Pemphigus is a severe autoimmune blistering disease affecting the skin and mucosa. Mortality is high in the absence of treatment. Nowadays, treatment is based mainly on corticosteroids and cytotoxic drugs; however, because of the rarity of the disease worldwide, there is not yet a standard treatment based on randomized controlled trials, and the treatment used is based mainly on the experience of experts. OBJECTIVE: The aim of this study was to compare the efficacy and safety of 4 treatment regimens for pemphigus vulgaris: prednisolone alone, prednisolone plus azathioprine, prednisolone plus mycophenolate mofetil, and prednisolone plus intravenous cyclophosphamide pulse therapy. METHODS: One hundred twenty new cases of pemphigus vulgaris were enrolled. These patients were randomly allocated into 1 of 4 treatment groups (each comprising 30 patients) and received prednisolone (P), prednisolone and azathioprine (P/A), prednisolone and mycophenolate mofetil (P/MM), and prednisolone and intravenous cyclophosphamide pulse therapy (P/PC). They were followed up for 1 year at the Pemphigus Research Unit. RESULTS: In groups P, P/A, P/MM, and P/PC, 23 (76.5%), 24 (80%), 21 (70%), and 22 (73.3%) of the patients, respectively, followed the regimen for the full 1-year period. The mean total dose of prednisolone administered in groups P, P/A, P/MM, and P/PC was 11631 mg (standard deviation [SD] = 7742), 7712 mg (SD = 955), 9798 mg (SD = 3995), and 8276 mg (SD = 810), respectively. The mean total dose of prednisolone in group P (prednisolone alone) was 11,631 mg, The mean total dose of prednisolone in the 3 cytotoxic groups was 8652 mg. By using analysis of variance, the difference was statistically significant (P = .047). In the cytotoxic groups, there was a significant difference between the P/A and P/MM groups (P = .007), but not between P/A and P/PC (P = .971), and P/MM and P/PC (P = .670). Side effects were not significantly different among the 4 groups. LIMITATIONS: Larger sample sizes and blind design are suggested for future studies. CONCLUSION: The efficacy of prednisolone is enhanced when it is combined with a cytotoxic drug. The most efficacious cytotoxic drug to reduce steroid was found to be azathioprine, followed by cyclophosphamide (pulse therapy), and mycophenolate mofetil.