Primary renal synovial sarcoma (SS) was first described in 2000 by Argani, with only a few subsequent cases being reported in the English literature. Herein, we describe a case of a 52-year-old woman who presented with right flank pain. Magnetic resonance imaging revealed a 6-cm mass in the lower pole of the right kidney. T1 and T2 weighted imaging revealed a heterogeneous mass with triple sign. There was post-contrast enhancement. Imaging, histology and immunostaining together made the diagnosis of SS of the kidney.