A new iridoid lactone, rehmaglutin C(4), and a new chlorinated iridoid glucoside, glutinoside (5), were isolated from Chinese Rehmanniae Radix, the dried root of Rehmannia glutinosa Libosch. [Kan-jio (in Japanese) from China]. Their absolute stereostructures were determined on the basis of chemical and physicochemical evidence and by use of the exciton chirality method for allylic benzoyl derivatives.