The results of experimental studies on establishment of the chemical structure of the first representative of a more polar steroid glycosides extracted from the plant Tribulus terrestris L. and designated conventionally as glycozide D are presented in the paper. By applying the classic chemical, physical and chemical methods of investigation it was determined that D is a glycozide tetraozid of diosgenin, in the carbohydrate chain composition of which enter two molecules of D-glycose and L-ramnose. The chemical structure of glycoside D looking as 3-O-β-D-glycopiranozil-(1→4)-O-α-L-ramnopiranozil-(1→2)-O-[α-L-ramnopiranozil-(1→4)]-O-β-D-glycopiranozid of diosgenin has been proved.