Kidney transplantation or renal transplantation is the organ transplant of a kidney into a patient who has the end-stage renal disease. Kidney transplantation is typically classified as deceased-donor (formerly known as cadaveric), or living-donor transplantation, depending on the source of the donor organ.

Living-donor renal/kidney transplants are further characterized as genetically related (living-related) or nonrelated (living-unrelated) transplants, depending on whether a biological relationship exists between the donor and recipient.

Exchanges and chains are a novel approach to expand the living donor pool. In February 2012, this novel approach to expand the living donor pool resulted in the largest chain in the world, involving 60 participants, organized by the National Kidney Registry. In 2014, the record for the largest chain was broken again by a swap involving 70 participants.

Indications
The indication for kidney transplantation is an end-stage renal disease (ESRD), regardless of the primary cause. This is defined as a glomerular filtration rate of < 15 ml/min/1.73 m2. Common diseases leading to ESRD include malignant hypertension, infections, diabetes mellitus, and focal segmental glomerulosclerosis. The genetic causes include polycystic kidney disease, a number of inborn errors of metabolism, plus autoimmune conditions such as lupus.

Diabetes is the most common known cause of kidney transplantation, accounting for approximately 25% of those in the US. The majority of renal transplant recipients are maintained on dialysis (peritoneal dialysis or hemodialysis) at the time of transplantation. However, individuals with chronic kidney disease who have a living donor available may undergo pre-emptive transplantation before dialysis is needed, while the odds of success are still favorable. If a patient is placed on the waiting list for a deceased donor transplant early enough, they may also be transplanted pre-dialysis.