Stable, free-flowing dispersions in organic liquids of rubbers in the form of discrete particles having an average diameter of from 100 to 3,000 nm which contain: A--as rubber, from 1 to 20% by weight, based on the total dispersion, of a crosslinked diene rubber or a crosslinked, rubber-like acrylate polymer; B--from 0 to 15% by weight, based on the total dispersion, of water in the form of a water-in-oil emulsion; C--as the continuous organic phase, from 99 to 45% by weight, based on the total dispersion, of a mixture of from 95 to 60% by weight of a liquid aliphatic hydrocarbon having up to 20 carbon atoms; or C.sub.6 -C.sub.12 aromatic hydrocarbon or a halogen derivative thereof and from 5 to 40% by weight of a C.sub.1 -C.sub.12 alkanol, a ketone containing up to 8 carbon atoms, a formamide or a nitrile containing up to 6 carbon atoms, and a process for their manufacture.