The invention comprises aldosterone of the formula: <FORM:0786562/IV (b)/1> and its mono-hydrate, and a process for their isolation from suprarenal glands whereby an extract obtained from the glands by known methods with the aid of a lipoid solvent is fractionated by distribution between an aqueous solvent and a water-immiscible solvent, and/or by chromatography, if desired in conjunction with the use of Girard reagents to recover the ketonic portion, and aldosterone or its hydrate is then isolated by crystallization of those ketonic fractions which are especially highly active in the metabolism of mineral substances, i.e. those fractions which have a marked effect in the organism on the balance of mineral matter, causing tenacious retention of sodium and a slight increase in potassium excretion compared with the effect of desoxycorticosterone. The distribution is preferably effected between water or 30 per cent aqueous methanol and petroleum ether, benzene or a halogenated hydrocarbon or mixtures thereof.  In examples: (1) freeze-dried beef suprarenal cortexes are extracted with acetone and 80 per cent aqueous acetone, the combined extracts evaporated and the aqueous residue extracted with petroleum ether and then with ethylene chloride; evaporation of the latter extracts yields a crude material which is completely defatted by distribution between aqueous methanol and petroleum ether, the aqueous phase is concentrated (below 50 DEG C.), extracted with ether-chloroform and the latter extract washed, dried and evaporated yielding a purified extract which is then fractionated by distribution chromatography, the stationary phase being kieselguhr-water and the mobile phase petroleum ether, benzene and chloroform; the fractions (analysed by paper chromatogram, U.V. spectra, reduction of silver diammine) containing aldosterone are then distributed on a second column of cellulose between 60 per cent aqueous methanol and toluene-petroleum ether, and aldosterone isolated as the hydrate from the combined fractions containing it by evaporation and recrystallization from acetone-ether containing a little water; (2) the defatted extract prepared in (1) is purified by adsorption chromatography on silica gel using methylene chloride, chloroform, acetone and methanol, then on cellulose using propylene glycol, cyclohexane, toluene and methylene chloride, and finally on cellulose, distributing between propylene glycol and benzene or on paper sheets between propylene glycol-toluene, or aqueous methanol-petroleum ether-toluene or benzene or ethyl acetate; (3) as in (1) but incorporating treatment with Girard reagent T in methanol, either after defatting or after the first fractionation; (4) as in (1) from pigs' suprarenal glands, distributing the initial fatty extract between aqueous NaCl solution (containing 30 per cent methanol) and petroleum ether before the kieselguhr fractionation; (5) as in (1), the second distribution (on cellulose) yielding 57 fractions, of which Nos. 32-39 furnish aldosterone.ALSO:Pharmaceutical preparations contain aldosterone or its hydrate in admixture with a solid or liquid carrier suitable for enteral, parenteral, or topical administration.  The compositions may include preservatives, stabilizing, emulsifying and wetting agents and other therapeutic agents.  Specified diluents and additives include:-water, gelatin, talc, lactose, sugar, starch, magnesium stearate, vegetable oils, e.g. sesame oil, gums, cholesterol, petroleum jelly, benzyl alcohol, polyalkylene glycols, sodium chloride, primary and secondary sodium phosphate, sodium carboxymethyl cellulose, sorbitan monolaurate ethylene oxide ether, mercury sodium thiosalicylate, and p-stearoylamino-phenyltrimethylammonium methyl sulphate.