Sue Westhead, 75, was given the organ by her mother Ann Metcalfe after she became ill as a teenager.
She had surgery at the Royal Victoria Infirmary in July 1973 and has surprised doctors who only expected the transplant to last for 20 years.
She said: “When I had my transplant, I thought I would be extremely lucky if I got five years.
“I got 50 years, thanks to our wonderful NHS, my mother and her genes. I know my mother would have been totally amazed her kidney gave me life for so long after her death.
“When I say I carry a little piece of her around with me always, I mean it. Thank you, Mam.”
Ann died 12 years later in 1985 at the age of 69 following a road accident.
Sue, of Houghton-le-Spring, Tyne and Wear, added: “If your loved ones are thinking of donating, do it.
“Just think of the joy you would bring to a person and their family who is leading a miserable, tied-down-to-dialysis life. They would be forever indebted.”
Consultant nephrologist Rachel Davison, at the Sunderland Royal Hospital where Sue is cared for, said: “This story is amazing.
“It shows how transplants can give people a life and lifestyle they simply would not have been able to have. We have lots more ways to treat people now and many of our patients live well using dialysis offered in our units, but also in their own homes.
“But for some, a kidney transplant offers a chance of return to a virtually normal life.”
Robert Hughes, of County Durham, has also celebrated 50 years since his life-saving kidney transplant. He had his operation in January 1974 after his brother John was a match.
South Tyneside and Sunderland NHS Foundation Trust’s Renal Unit hosted a celebration for both recipients.
Consultant nephrologist James Andrews said: “It’s a remarkable milestone and as a department we were grateful for the chance to acknowledge the treatment which has made a difference to his life and the gift his brother gave.” Recalling the op 50 years ago. Robert said: “In the corridor, I was going into one theatre and my brother was going in the other, I shook his hand and we had a bit of brotherly banter.
“After the transplant they gave me half a pint of Guinness to help get some iron in me and to see if it worked. John saved my life.
“After the transplant, he wasn’t just my brother, he was my best friend, I just couldn’t thank him enough.
“I felt unbelievable afterwards. After my transplant, my life totally changed, I could live normally.
“Our dad had bought us both a gold bracelet after our surgery, my brother’s said ‘For courage’ and mine said ‘For valour’.
“I have six-monthly checks at the hospital and every time I go through the doors I get a smile because they know they’ve seen me for so long.”