Abstract: The occurrence of fossil eggs in the Late Cretaceous of the Tiantai basin,Zhejiang,southeastern China,is reported.They include the new family Testudoolithidae fam.nov.,the new genus Tiantaioolithus gen.nov.and five new species,Dendroolithus shuangtangensis sp.nov.,Elongatoolithus chichengshanensis sp.nov.,Elongatoolithus laijiaensis sp.nov.,Spheroolithus jincunensis sp.nov.and Tiantaioolithus jiangi sp.nov.The eggs found in the Chichengshan Formation are the most varied,including Elongatoolithidae,Phaceloolithidae,Spheroolithidae and Testudoolithidae fam.nov.,while in the Laijia Formation fossil eggs are scarce and only Elongatoolithidae and Spheroolithidae are found.The fossil eggs are Late Cretaceous in age.It is inferred that the cause for the disappearance of the Tiantai eggs was due to the cooling of the cli-mate,which led to the failure of hatch the eggs normally.The lowering of the hatching rate and breakdown of the reproductive chain might be one the causes for the extinction of dinosaurs.