Three trepanned crania from 4th–3rd century BC low-ranking burials in Gorny Altai are described. The probable motives behind such operations are discussed, their effi ciency is assessed, and techniques are reconstructed using optical macroscopic examination, multi-slice computed tomography, X-ray fl uorescence, and mass spectrometry of bone tissue. Trepanations were apparently medical rather than ritual. Our data support the idea that the 4th–3rd century BC inhabitants of the Altai-Sayan Highlands had enough knowledge and skills to perform complex cranial surgery. Because the instruments were made of tin bronze, and the Minusinsk Basin was the only place in southern Siberia where such bronze was smelted (by the Saragash people), at least two successful trepanations were probably performed by immigrants from that region.
