The kidney was an excretory organ incorporated as part of the renal system. It functioned to maintain the water, the acid-base concentration, and filter the blood; the waste products were excreted as urine. The organ was described by the Malcorians as the renal organ. Diffrent species can have a diffrent number of kidneys. For example members of the Yarkora species have four kidneys. For humans, they only possess two inside their chests and one is capable of functioning properly even if the other is removed; however, failure of both is fatal and must be treated with dialysis or transplantation from another human.
Hitting a person in the kidneys caused extreme—often disabling—pain for the victim. Most Humanoids at a certain advance age often suffered from Zithrom's syndrome, which resulted in shrunken kidneys, among other symptoms. Kidney stones could accumulate within the kidneys and be passed from the body.
Some Kidneys from species were a delicacy in some cultures such as Denobulan lemur kidneys, including Salarian kidneys when they were primitive by the time the Protheans when they first discovered them.
Yuuzhan Vong typically lacked kidneys.