In relation to etiology, pathophysiology and therapy of surgical diseases, influence of estrogen has aroused various discussions and its assay has become quite necessary. However, the methods of measuring urinary estrogen such as those of Brown, Bauld, Cohen or radioimmunoassay available at present have some disadvantages in which procedures are complicated and take quite some time until the results can be obtained and special apparatuses are required. For these reason, I have devised a simple method of applying E(3)-Kit method to measure estrogen of a high concentration in pregnant women to measure urinary estrogen of non-pregnant women as well as that of men. With 9-hours night urine as the material, estrogen is allowed to be absorbed by a 50ml of Amberlite XAD-2, and this is then extracted with methanol, and the condensation of the extract was accomplished by evaporation of the methanol. Then the colorimetric quantitation is done by E(3)-Kit method. By this method it is possible to measure over 5μg/9hrs. of estrogen. In calculating the dose response curve by this method, the coefficient of correlation was as high as 0.998, although the recovery rate was 43.5 % . Furthermore, as the quantity of estrogen excreted in the night urine was found to be in a direct proportion to that excreted in the day urine, the multiple of 24/9 was made to represent the quantity of estrogen excreted in one-day urine. The same urine sample was then assayed by this method as well as by Brown's fluorescent method, and the coefficient of correlation was calculated. Such tests showed that the coefficient was 0.763. These results indicate that this assay method can be sufficiently applicable to the clinical practice. The quantity of estrogen excreted in the urine was measured by this method in the cases with various diseases having the sex limit. The urinary estrogen level in the menstruants with aortitis syndrome was distinctly lower than in the control menstruants group, but in the cases of aortitis syndrome after menopause it did not show any outstanding differences. The estrogen level in the cases of arteriosclerosis obliterans and Buerger's disease of males tended to be somewhat higher than normal males.