Granulomatous disease of the breast is a rare differential diagnosis with an estimated incidence of 2.4 per 100,000 women and 0.37% in the US. Idiopathic Granulomatous Mastitis (IGM) is a non-infectious inflammation that was first described in 1972 by Kessler and Wolloch. It is an infrequently reported chronic disease of the breast of unclear etiology. Although its etiology has not been explained definitively, various factors including autoimmunity are probably involved. It has been suggested that breast feeding and use of oral contraceptives may have a role in IGM. It has various spectrum of presentations including single or multiple painful or painless breast swelling(s), breast ulcers, and sinus or abscess formation. Definitive diagnosis is through histopathological evaluation of the breast tissues achieved by core needle biopsy (CNB) showing noncaseating granulomas with chronic inflammatory cells such as histiocytes and multinucleated giant cells. This study was performed to evaluate the outcome of nonsurgical treatment of IGM with oral corticosteroids in correlation with pathological changes before and after treatment.