Milk of calcium in a renal cyst is a rare condition. The authors report a case evaluated by ultrasonography, computed tomography (CT) and magnetic resonance imaging (MRI). A 58 year - old women presented with diffuse abdominal pain. Ultrasonography showed a left upper pole cystic lesion with echogenic component in the dependent portion causing shadowing. CT showed a cyst with layering milk of calcium. On MRI, the milk of calcium sediment had low signal intensity on T1 and T2 weighted images.