The modification of the Touchstone‐Green technique used for determining urinary estriol is described. The urinary estriol excretion in 116 normal pregnant women and in 355 patients with complicated pregnancy is also presented. No fetal loss in pregnant women with complications when estriol excretion remained in the normal range. Very low estriol values below 4 mg. per day were encountered in the patients with anencephalic fetus, intrauterine death and hydatidiform mol