Easter Island is the most isolated piece of inhabited land in the world. It exhibited an unique megalithic culture1-3, involving the sculpting of giant statues (moai) especially between AD ~1400 and ~16804 when, for unknown reasons, the culture suddenly collapsed. The island is also of interest in relation to Pleistocene climatic change as CLIMAP5 predicted no reduction of sea-surface temperatures for this part of the Pacific at 18,000 yr BP. We have obtained fossil pollen records covering the past 37,000 yr from three craters on the island. They suggest that the late Pleistocene climate was cooler and/or drier than the present one. They also suggest the former existence of forest on the island, and its decline in the last millennium. This decline was probably due to deforestation by man and could have caused the cultural collapse.