Emulsifier-free antifoams are obtainable by mixing a) from 80 to 99% by weight of at least one finely divided, virtually water-insoluble, inert solid with b) from 1 to 20% by weight of at least one hydrophobic, organic compound which has an antifoam action and is solid at room temperature in the absence of a solvent in a shear gradient such that the particle size of the compounds (b) which have an antifoam action is reduced to a mean particle size of from 0.5 to 15 .mu.m, emulsifier-free oil-in-water dispersions of mixtures of (a) and (b) are prepared by mixing the component (a) in an amount of from 80 to 99% by weight with the compounds of component (b) in an amount of from 1 to 20% by weight in the absence of emulsifiers in an extruder or kneader in a manner such that the mean particle size of the component (b) in the mixture is brought to 0.5 to 15 .mu.m, at up to 100.degree. C., and emulsifying the mixture in water, and the oil-in-water dispersions thus obtainable are used as antifoams and/or deaerators for aqueous, disperse or nondisperse liquids, in particular as antifoams and/or deaerators in the paper industry, in the food industry and in wastewater treatment plants.