Recovery of a phenolics-depleted natural mixture of conjugated oestrogens from the urine of pregnant mares comprises (a) providing a liquid urine (which comprises a urine freed from mucous and solids, a concentrate of the latter or a urine retentate obtained by membrane filtration) and treating it with a water-soluble base to give a pH of at least 12 and subsequently treating with aqueous acid to adjust the pH to 5-8.5； (b) contacting the urine with a hydrophobised silica gel to adsorb the conjugated oestrogens and separating the gel from the mixture； (c) washing the gel with an aqueous buffer adjusted to pH 5-7； and (d) eluting the oestrogens from the gel using a mixture of water and a water-miscible solvent selected from ethers, lower alcohols and lower aliphatic ketones, and optionally concentrating the eluate；
