Estriol 3-glucuronide, or oestriol 3-glucuronide, also known as estriol 3-ò-<small>D</small>-glucosiduronic acid, is a natural, steroidal estrogen and a glucuronic acid (ò-<small>D</small>-glucopyranuronic acid) conjugate of estriol. It is found in the urine of women as a reversibly formed metabolite of estriol. The positional isomer of estriol 3-glucuronide, estriol 16ñ-glucuronide, also occurs as an endogenous metabolite of estriol, but to a much greater extent in comparison.