According to the 2008 Guinness Book of World Records the tallest living man is 37 year old Ukrainian Leonid Stadynk, who measures 8 feet, 5 inches (2.59 meters) tall and weighs 440lbs. Apparently his excessive growth started when he was 14 years old, after having brain surgery. He developed a pituitary gland tumor, causing it to secrete large amounts of growth hormone. This is referred to as acromegalic gigantism.
A news report from 2006 claims that he had grown 2cm in the previous year. Doctors assume that he will keep on going... Check the AP video below to see what he has endure: