The invention comprises 16-alkylestratriene-3,16,17-triols and ethers and esters thereof of the general formula: <FORM:0804789/IV (b)/1> (wherein R and R1 are each hydrogen, a hydrocarbon radical containing less than nine carbon atoms or an acyl radical of a hydrocarbon carboxylic acid containing less than nine carbon atoms, R11 is hydrogen or an acyl radical of a hydrocarbon carboxylic acid containing less than nine carbon atoms, and the term "lower alkyl" refers to alkyl radicals containing less than nine carbon atoms), and their preparation by treating a ketone of the general formula: <FORM:0804789/IV (b)/2> with an alkylmagnesium halide, decomposing the organometallic intermediate with an acidic reagent and isolating the product. Starting materials in which R is hydrogen are not preferred owing to the competing reactions which they may undergo. The stereochemical configuration of the 17-substituent of both the starting materials and reaction products is the same as that of natural estradiol, i.e. the b -configuration. By reacting an excess of the alkylmetallic reagent with an ester of 16-ketoestradiol, addition to the ketone group is accompanied by conversion of ester groups present to hydroxyl; the same product may be obtained by employing an equivalent of alkylmagnesium halide and conducting the hydrolysis of the ester groups as a separate operation. Ethers and esters of the parent 16-alkylestratriene-3,16,17-triols are prepared by etherification and esterification of any hydroxy groups present. The addition of an alkyl-magnesium halide to a ketone group leads to the formation of mixtures of stereoisomers but in practice the stereoisomer in which the 16-hydroxy group is cis to the 17-b -substituent generally predominates and on recrystallization the product consists substantially of this isomer. The corresponding trans-isomer is obtained by chromatographic fractionation of the mother liquors from the crystallization above, or by converting a 17-ketone of the estrone series to its 16-alkylidene derivative followed by epoxidation and reduction, and may be converted into ethers and esters in the same way as the predominating stereoisomers above. Examples describe the preparation of 3 - methoxy - and 3 - ethoxy - 16 - methyl 1,3,5(10) - estratriene - 16,17 - diol (from methylmagnesium bromide and 16-ketoestradiol 3-monomethyl and 3-monoethyl ether respectively); 3-methoxy-16-ethyl-1,3,5(10)-estratriene - 16,17 - diol (from ethylmagnesium bromide or iodide and 16-ketoestradiol-3-monomethyl ether); 3-benzyloxy- and 3-(p-methylbenzyloxy) - 16 - methyl - 1,3,5(10) - estratriene-16,17-diol (from methylmagnesium bromide and 16 - ketoestradiol 3 - monobenzyl and 3 - mono-(p-methylbenzyl) ether respectively); 3-benzyloxy - 16 - propyl - 1,3,5(10) - estratriene - 16,17-diol (fromn-propylmagnesium bromide and 16-ketoestradiol 3-monobenzyl ether); 16-methyl-1,3,5(10) - estratriene - 3,16,17 - triol (from methylmagnesium bromide and 3,17-diacetoxy-1,3,5(10) - estratrien - 16 - one); 3,17 - dimethoxy - and 3,17 - diethoxy - 16 - methyl-1,3,5(10) - estratrien - 16 - ol (from methyl-magnesium bromide and 16-ketoestradiol dimethyl and diethyl ether respectively); 3-methoxy - 16 - methyl - 17 - acetoxy -, - 17 - butyroxy-, -17-benzoyloxy-and-17-cyclopentylpropionoxy - 1,3,5(10) - estratrien - 16 - ol (from 3 - methoxy - 16 - methyl - 1,3,5(10) - estratriene - 16,17 - diol and acetic anhydride, butyric anhydride, benzoyl chloride and b -cyclopentylpropionyl chloride respectively; 3, 17 - diacetoxy - and 3, 17 - dipropionoxy - 1,3,5(10) - estratrien - 16 - ol (from 16 - methyl-1,3,5(10) - estratriene - 3,16,17 - triol and acetic anhydride and propionic anhydride respectively); 3-methoxy-16-methyl-1,3,5(10)-estratiene-16,17-diol diacetate (from 3-methoxy - 16 - methyl - 1,3,5(10) - estratriene - 16,17-diol and acetic anhydride in the presence of p-toluenesulphonic acid); 3-ethoxy-16-methyl - 1,3,5(10) - estratriene - 16,17 - diol dipropionate (from 3 - ethoxy - 16 - methyl - 1,3,5(10) - estratiene - 16,17 - diol and propionic anhydride in the presence of p-toluenesulphonic acid), and the preparation of 3-methoxy - 16 - methyl - 1,3,5(10) - estratriene-16,17-diol, isomeric at position 16 with the major product of the organometallic reaction above (by reacting 3-methoxy-16-methyl-16,11-epoxy - 1,3,5(10) - estratrien - 17 - one with lithium aluminium hydride) and its conversion to 3 - methoxy - 16 - methyl - 17 - acetoxy - 1,3,5(10) - estratrien - 16 - ol by the action of acetic anhydride under mild conditions. 16 - Ketoestradiol 3 - monoethyl and 3 - mono-(p-methylbenzyl) ether are prepared by reacting 16-ketoestradiol in ethanol in the presence of potassium carbonate with ethyl iodide and p-methylbenzyl chloride respectively. 3,17 - Diacetoxy - 1,3,5(10) - estratrien - 16 -one is obtained by reacting 16-ketoestradiol with acetic anhydride in pyridine. 16-Ketoestradiol dimethyl and diethyl ether are prepared by reacting 16-keto-estradiol with potassium tert.-butoxide and subsequently with methyl iodide and ethyl iodide respectively. 3 - Methoxy - 16 - methyl - 16,11 - epoxy - 1,3,5(10) - estratrien - 17 - one is obtained by reacting estrone methyl ether with paraformaldehyde and dimethylamine hydrochloride in isoamyl alcohol and treating the resulting 3-methoxy - 16 - methylene - 1,3,5(10) - estratriene-17-one with hydrogen peroxide. The acetonide of 3-methoxy-16-methyl-1,3,5(10)-estratiene-16,17-diol is prepared by reacting the diol with acetone in the presence of hydrochloric acid.