A new climatic time series has been determined from delta O-18 analysis of a 2083 m ice core drilled at Vostok Station. The site is located on the high Antarctic Plateau, where the ice thickness is about 3700 m. The isotope profile covers the last 150 kyr, back to the ice age which preceded the last interglacial, and has essentially been undisturbed by flow conditions. The results indicate that the present Holocene was preceded by a long glacial period marked by two relatively warm interstadials. The well marked last interglacial was significantly warmer than the Holocene and the end of the previous glacial was quite similar to the last glacial maximum. The presence of a roughly 40 kyr cycle in the Vostok record strongly supports the role of orbital forcing in determinig climatic change.