John Triteos was matched last month with someone living three miles away from his Highgate home. He had the transplant in the Royal Free Hospital on 6 June, but began to deteriorate last week. He died on Tuesday.
It had taken a year to find an American to help Mr Triteos, 33, a professional gardener. Her marrow was a perfect match. But when she withdrew her offer in February, his family tried to recruit donors from their Greek Cypriot community. Mr Triteos's girlfriend, Jane Huxley, said: 'It wasn't an identical match but it was the best we could find. John was beginning to slip away and we couldn't wait any longer.
Four years ago his sister died of leukemia.
The Anthony Nolan Bone Marrow Trust, based in Hampstead, began an international search to find a donor; 1,500 potential donors have registered. The Anthony Nolan Bone Marrow Trust: 071 284 1234.