Retained surgical sponges, so called gossypiboma (or textilomas), are very rare complications after surgical procedures. The estimated incidence is approximately 1/10001500 surgical operations but the actual incidence rate is unknown because of its medicolegal aspects. Clinical manifestations may occur early or late after surgery, depending on the type of inflammatory reaction. Ultrasound and computed tomography (CT) imaging and magnetic resonance imaging are valuable tools in diagnosing gossypibomas. Gossypiboma may appear like low density, high density or complex masses with CT. Sometimes high density capsule may be seen. Internal calcification is a rare finding. Gossypibomas may look like abscess, hematoma, pseudocyst, or tumors. Here in, we presented a rare renal gossypiboma case mimicking a renal tumor. Gossypiboma should be kept in mind at differential diagnosis of renal masses who had undergone renal surgery before.Keywords: Gossypiboma, renal neoplasms, surgical sponge.