The renal sinus is a deep recess located at the medial aspect of the kidney surrounded by the renal parenchyma. It contains within it the collecting system of the kidney, lymphatics, nerves, and renal blood vessels. The remainder of the sinus is filled with adipose and fibrous tissue. A variety of pathological conditions arise from the different tissues in this site. The aim of this review is to explore and illustrate the common and less common processes affecting the renal pelvis.