A method for obtaining an extract from a natural mixture of conjugated estrogens from the urine of pregnant mares (PMU) by solid-phase extraction on semipolar adsorption resins in which the resulting extract meets the pharmaceutical specifications for conjugated estrogens and the content of free estrogens is minimized even if old pregnant mares' urine and/or pregnant mares' urine which has been stored or transported at elevated temperatures is used.
