When a kidney from another person is put into someone whose kidneys are no longer working, it's called a kidney transplant. Usually one kidney is put in during a transplant. One healthy kidney can do the work of two. The transplant involves an operation, which usually takes about three hours. Once you have the transplant operation, you'll take medications as long as you have a working transplant. These medicines help your body accept the kidney and are called anti-rejection medicines.