Estimating the age of an ancient yew is hard because the heartwood decays, and with it go the growth rings that would settle the question. The Fortingall Yew lost its centre by 1770. In 1769 the trunk was recorded as 52 feet in girth, an extraordinary measurement; now the tree is split into several separate stems that look almost like a small grove of trees, with the old trunk reduced to fragments. Estimates of the age range from a relatively modest 2,000 to 3,000 years up to as much as 9,000 years. Forestry and Land Scotland settle on 5,000. Whichever figure is closest, the tree was already ancient when Christianity arrived in Scotland.

By 1833 it was noted that large arms had been removed from the yew, and even masses of the trunk had been carried off, to be made into drinking cups and other curiosities. A souvenir-cup made from the wood of the world's oldest tree was, evidently, the kind of thing a Victorian gentleman wanted on his sideboard. In 1785 a low wall was built around the tree to protect it. The wall is still there. The tree is still visible. In 2019 the Tree Warden for Fortingall and the Tayside Biodiversity Community Partnership warned that modern tourists, ripping off branches for souvenirs of their own, were posing a renewed threat to the tree's survival.

The Royal Botanic Gardens in Edinburgh have taken cuttings from the Fortingall Yew to form part of a mile-long hedge in the Yew Conservation Hedge Project. The aim is to preserve the DNA of Taxus baccata from the UK's most ancient specimens, because yew populations worldwide are threatened by felling and disease. So pieces of the Fortingall Yew now grow in Edinburgh, and the DNA of something that may predate the Bronze Age has been pulled, scientifically, into the 21st century. Genetic insurance against a future in which the original is lost.

Local legend insists that Pontius Pilate was born in the yew's shade and played beneath it as a child. Dr Paul Philippou, an honorary research fellow at the University of Dundee, has politely pointed out that this is historically impossible: Pilate was born before the Romans had reached this part of Scotland. But the legend persists, perhaps because legends accumulate around very old trees in the way that lichen does. Reverend James MacGregor, who wrote the Book of the Dean of Lismore, served at the church here in the 16th century. The Iron Age cult centre that almost certainly preceded the church may itself have been built around the tree. Yews have always been sacred in northern Europe. This one has had the longest time to gather meaning.