Abstract: Altogether 12 fossil bone samples in two batches were dated with accelerator mass spectro-metry radiocarbon ( AMS-C14) technique. In comparison with the first batch of AMS-Cl4 da-tes, new combined dating results push the age for the cultural phase further back to 29- -24ka before present, while the time of filling of the Lower Recess remains unchanged, which hadstarted at about 34--33 ka ago (see table 1).
This new age assignment is much older than coinmonly accepted conventional radiocarbonages of 10470 a for the cultural phase and 18340 a for the deposits in the Lower Recess. Wethink the AMS-C14 dates are more compatible with geological and archaeological evidences.(1) Human skulls found in this site were unanimously classified as late Homo sapiens.Mor phologically these skulls show more primitive features than other members of Later Homo sapiens like Ziyang Man and Chuandong Man of Puding, and are different in species levelfrom that of Chinese early neolithics. It must have taken quite a long time for the evolutionprocess when Upper Cave Men gradually transformed into Homo sapiens, which would contra-dict the conception that the Upper Cave Men lived at the very end of Late Pleistocene.
(2) 19-11 ka was an extremely cold period, while 34--24 ka was a relatively warm in-terstadial during the Wurm Glacial. Upper Cave fauna contained tropic animals like Pugumalarvata and Acinonyx cf. jubatus, but no Coelodonta antiquitatis nor mammuthus which werevery popular during cold glacial time in North China. AMS -Cl4 age determination of 34--24ka would better fit the composition of the fauna.
No difference in culture nor fauna between upper and lower parts of the cultural depo-sits has been reported, still as no samples from the uppermost layers of this site has been datedyet, the possibility that the Upper Cave Culture had lasted somewhat later than 24 ka can notbe completely excluded.

Key words: Upper Cave of Zhoukoudian; Palaeolithic chronology; Accelerator radiocarbon dating