Purpose: Idiopathic granulomatous mastitis is a rare, benign breast disease of unknown etiology characterized by chronic inflammation. Distinguishing it from either breast carcinoma or infections both clinically and radiologically can be difficult. The purpose of this study is to review the characteristics of idiopathic granulomatous mastitis in a large series of patients and to evaluate the effectiveness of the treatment methods during a long follow up period. Patients and Methods: Patients treated with the diagnosis of idiopathic granulomatous mastitis between 2005 and 2009 were included in the study. Patients clinical, radiological, and histopathological findings were retrospectively obtained from the files. Results: Fifty-one female patients with a median age of 33 were included. All patients had a history of childbirth and breastfeeding. Forty-five patients (88.2%) were premenopausal. The main clinical feature was a mass in the breast in all patients and clinical findings suggesting an infection accompanied the mass in seven patients (13.7%). Surgery was the definitive procedure in all patients. Wide local excision was the treatment of choice in 50 patients (98%) whereas modified radical mastectomy was performed in one patient. Median followup time was 38 months and three patients (5.9%) presented with recurrence. One patient recurred twice and total mastectomy with reconstruction was performed. Two other patients were treated with further wide local excisions. Conclusion: Surgeons, radiologists, and pathologists should be familiar with idiopathic granulomatous mastitis and multiple assessments including clinical, radiological, and histopathological examinations are required for an accurate diagnosis. Long-term follow-up preferably by the same doctors is necessary for the management of such a difficult disease.