This clinical study was conducted to present clinical, radiologic, and histopathologic features of Granulomatous Mastitis (GM) and evaluate the result of surgical and steroid treatment. Sixteen cases diagnosed histologically as GM were reviewed. Patient characteristics, clinical presentation, radiologic imaging, microbiologic, histopathologic assessment, treatment modalities, recurrence, morbidity, and follow-up data were analyzed. Majority of the patients were child bearing age and all of the patients had a history of breast feeding. Radiologic findings were nonspecific. Histopathology showed the characteristic distribution of granulomatous inflammation in all cases. In 12 cases, surgical excision of the lesion with negative margins was performed. Four cases required quadranectomy because of wideness of the disease. Three patients who had local reoccurrence and three resistant patients were treated by oral prednisone after surgical attempt. Complete remission was obtained and no further recurrence was observed in this patients. GM predominantly occurs in premenopausal women and the clinical symptoms might be misjudged as breast cancer. Histopathologic examination remains the gold standard for the diagnosis. Wide excision of the lesions is the recommended therapy and we suggest steroid therapy in resistant or recurrent disease following the idea that the disease has an autoimmune component.