Idiopathic granulomatous mastitis (IGM) is a rarely seen benign chronic inflammatory breast disease. Etiology is still unknown, many factors mainly including hormonal factors are proposed. Clinical findings include inflammation of the breast, induration, palpation of a mass galactorrhea and retraction of the nipple. Unilateral, usually right sided involvement is encountered. IGM may mimic fibroadenoma, fibrocystic changes, abscess and especially malignancy both clinically and radiologically. Although definite diagnosis is made by cytologic or histopathologic evaluation, radiological evaluation plays an important role in diagnosis and differentiating it from malignancy. Mammography (MG) and ultrasonography (US) are used basically for the diagnosis, but due to wide spectrum and low sensitivity, the findings are challenging. The most common finding of MG is ill-defined asymmetrical density that does not cause mass effect. On US, the radiological finding spectrum is quite wide. On conventional magnetic resonance imaging (MRI) lesion may demonstrate irregular or spiculated contours which may lead to misdiagnosis. However dynamic contrast-enhanced MRI plays an important role in differentiating the lesion from malignancy if a benign type (increasing contrast enhancement) Type 1 signal intensity time curve is obtained. On the other hand, sometimes Type 2 (plateau type) or even malignant type (early washout) Type 3 curve can be obtained. In these cases differentiation from malignancy by radiological means is quite difficult. New MRI techniques including diffusion MRI and MR spectroscopy (MRS), to our knowledge, are not reported yet. In this report MG. US, dynamic contrast-enhanced MRI,diffusion MRI and MR spectroscopy findings of IGM will be presented and the differential diagnosis will be discussed.