Several new β-hydroxyketones having the formula CH3R′C(OH)CH2COCH3have been prepared by the action of Grignard reagents on 2,4-pentanedione. With benzyl-,o-xylyl-,p-xylyl-, 3,4-dimethylbenzyl-, 2,5-dimethylbenzyl-, 3,5-dimethylbenzyl-, and α-naphthylmethyl-magnesium chlorides, 60 to 75% yields of the β-hydroxyketones were obtained. Phenyl-,p-tolyl-, andp-trifluoromethylphenyl-magnesium bromide and 2,4-dimethylbenzylmagnesium chloride gave lower yields, whereas with α-naphthylmagnesium bromide no β-hydroxyketone was formed. The β-hydroxyketones were separated from non-ketonic by-products by means of Girard's reagent T or P. Solid derivatives of the β-hydroxyketones could not be prepared.