During the course of our studies on the biologically active asclepiadaceous glycosides, several oligosaccharides were isolated from hydrolysate of the glycoside which showed positive Keller-Kiliani reaction due to 2-deoxysugar contained. Four new oligosaccharides: neocondurangotriose from Condurango Cortex, dregeatriose from Dregea volubilis, glaucobiose from Cynanchum glaucescens, and wilforibiose from C. wilfordi were elucidated to have the structures (14), (15), (11), and (12) respectively on the bases of chemical and spectroscopic data. Characteristic glycosidation shifts were observed among the 2,6-dideoxysugars and the related oligosaccharides and glycosides. These shifts seemed to be separated into two categories which are ascribed to the orientation of the substitution of the ProR(β)carbon in Fig. 6.