Excess molar volumes of twelve binary nitrile+ketone mixtures (acetonitrile, butyronitrile or pentanenitrile+propanone, +butanone, +2-pentanone or +3-pentanone) have been determined from density measurements at 298.15 K using a vibrating-tube densitometer. Excess molar volumes for these mixtures are negative except for butyronitrile or pentanenitrile+propanone.