Abstract: Fluid organopolysiloxane antifoaming compositions, devoid of inorganic filler material and adopted for use in both nonaqueous and aqueous systems, for example detergent powders and liquids and crop-protection formulations, characteristically having a viscosity of less than 50,000 mPa.s at 25.degree. C., include (A) at least one substantially linear polydimethylsiloxane polymer, (B) a methylpolysiloxane resin comprising recurring structural units of the formulae R(CH.sub.3).sub.2 SiO.sub.0.5 and SiO.sub.2, wherein R is an alkyl radical containing from 1 to 3 carbon atoms, or a vinyl radical, with the ratio of the number of R(CH.sub.3).sub.2 SiO.sub.0.5 recurring units (M units) to the number of recurring SiO.sub.2 units (Q units) ranging from 0.4 to 1.2, and (C) a cyclic polydiorganosiloxane of the formulae: ##STR1## wherein the symbols R', which may be identical or different, are each a radical R or a hydrogen atom, and n is an integer ranging from 3 to 15.