Compositions comprising (A) an organosilicon compound of the formula R.sub.a(R.sup.1O).sub.bR.sup.2.sub.cSiO.sub.(4-a-b-c)/2 (I) in which R.sup.2 independently denotes a monovalent, SiC-bonded, optionally substituted, aliphatic cyclic or aliphatic branched hydrocarbon radical having at least 3 carbon atoms, R, and R.sup.1 are hydrogen or hydrocarbon radicals, the sum a+b+c.ltoreq.3, the organosilicon compound has at least one unit of the formula (I) with c other than 0, and in at least 50% of all of the units of the formula (I) in the organosilicon compound the sum a+b+c is 2; at least one additive (B) selected from (B1) filler particles and/or (B2) organopolysiloxane resin(s) and optionally (C) an organosilicon compound which has units of the formula (III), R.sup.5.sub.g(R.sup.6O).sub.hSiO.sub.(4-g-h)/2 where R.sup.5 and R.sup.6 are hydrogen or a hydrocarbon radical, g+h.ltoreq.3 and in at least 50% of the units (III), g+h=2, are highly effective and long lasting defoamers.