[en] Model experiments were conducted to study the effect of a highly purified preparation of specific estrogen-binding protein (SEBP) on the intensity of estradiol and testosterone metabolism under the influence of enzymes in liver homogenate from female rats, not containing SEBP. The liver of mature female rats was homogenized in two volumes of 50 mM Tris-HCl buffer, pH 7.5, containing 600 mg% of glucose. The tritium-steroid was preincubated for 15 min at 0-4 C with 0-4 microg of the preparation of SEBP (200 microl). A standard preparation of partially purified SEBP was obtained from liver cystosol of mature male rats; affinity chromatography on estradiolagarose was used. It is shown that SEBP can really take part in regulation of the dynamics of sex steroids in the liver. E₁ did not affect the metabolic rate of H 3-E₂ by liver homogenate from females, but caused marked acceleration of H 3-E₂ metabolism by male liver homogenate