Dialysis is a form of kidney replacement therapy used when the kidneys can no longer adequately remove waste and excess fluid from the body. The two major forms are hemodialysis and peritoneal dialysis. Hemodialysis uses a machine and a special filter called a dialyzer to clean the blood, while peritoneal dialysis uses the lining of the abdomen as the filtering surface. Both approaches can help perform some of the functions normally carried out by healthy kidneys. Dialysis does not cure kidney failure, and treatment needs vary between individuals. For some patients, kidney transplantation may be another option. This article explains how the main types of dialysis work and the factors that may influence kidney replacement therapy choices.