Background: Immunosuppressive drugs have received the most attention for Idiopathic Membranous Nephropathy (IMN) that include alkylating agents such as tacrolimus and cyclosporine. Objectives: This study was aimed to evaluate the efficacy of tacrolimus versus cyclosporine in the treatment of IMN in the Western region of Iran. Methods: This clinical trial and double-blind study was performed on IMN patients based on the primary biopsy with a range of 15 to 70 years. The patients with secondary membranous nephropathy such as hepatitis B, hepatitis C and systemic lupus erythematosus were censored from the study. Group C was treated with cyclosporine 3 -6 mg/kg/d and a low dose of prednisolone and Group T was treated with tacrolimus 0.05 mg/kg/d and low dose of prednisolone. Results: 68 patients were entered in our study, 34 patients were randomly selected in Group T and 34 patients in Group C. The 24-hour urine protein reduced significantly in the two groups after the 3rd and the 6th month compared with the baseline. Uric acid increased in Group T after 3 and 6 months compared with the baseline (P < 0.05), but there was no significant difference in Group C. Creatinine clearance increased in two groups after 3 and 6 months compared with the baseline, however, it has been just as significant in Group T after 6 months. There was no significant difference in the two groups after 3 or 6 months from the first dialysis. Conclusions: Cyclosporine and tacrolimus reduce proteinuria and serum creatinine after 6 months. Nonetheless, tacrolimus reduces urea and cyclosporine increases it. However, since the prevalence of the side effects of both drugs is similar, tacrolimus has better results in the treatment of IMN patients compared with cyclosporine.