The only chimpanzee fossils known to science have been unearthed in Kenya, the journal Nature reports.
The three 545,000-year-old chimp teeth were dug up in the country's Tugen Hills and probably belonged to the same individual, the US discoverers say.
Plenty of fossils belonging to early human ancestors, or hominids, have been found at dig sites all over the world.
But until now, scientists had not identified a single fossil belonging to humankind's closest living relative.
The teeth were excavated from the Kapthurin Formation of the Tugen Hills late in 2004.
"Once you realise what they are, they're dead ringers," Professor Sally McBrearty, of the University of Connecticut, in Storrs, US, told the BBC News website.
"The thick bases of the incisors, in particular, are very characteristic of chimpanzees and also the fact that all of the teeth have thin enamel.
"The molars you might think: 'maybe this is human'; but the cusp pattern isn't really right."
The chimp probably died on the shore of a lake in a wet, wooded habitat.