The small quantity of obsidian used by the Aceramic Neolithic occupants of Cyprus was imported, there being no source on the island. The chemical composition, determined by neutron activation analysis, of six samples of obsidian from Kalavasos-Tenta indicates that they were derived from the central Anatolian, Göllü Dag Çiftlik: Group 2b) source. On the basis of chemical composition, obsidian from five Cypriot Aceramic Neolithic sites has the same provenance. Our data suggest that the fragments we analyzed were not derived from a single core and, because obsidian occurs throughout the Aceramic period of occupation of Kalavasos-Tenta, it appears unlikely that the 36 artifacts recovered from the site represent a one- time transfer of material. This suggests an enduring supply, and implies to us that the inhabitants of Kalavasos-Tenta were never completely isolated from the mainland.