The present invention concerns polymer blends and processes for the preparation thereof. The present blends contain a) 5 to 95 parts by weight of poly(2,6-dimethyl-1,4-phenylene)ether, b) 95 to 5 parts by weight of a second polymer which is immiscible therewith, and c) a component (a compatibilizer) which enhances the compatibility of the polymers. According to the invention the component enhancing the compatibility of the polymers comprises 0.1 to 10%, preferably about 1.5 to 10%, calculated on basis of the total weight of components a and b, of at least one compound C, which has the formulaA.sub.i --B.sub.j IwhereinA stands for a group which contains at least one ring with 3 to 7 members, capable of forming ring-to-ring interactions with the phenyl rings of poly(2,6-dimethyl-1,4-phenylene)ether,B is a polar group,i is an integer 1 to 20, andj is an integer 0 to 20,whereati+j is greater than or equal to 2,the melting point of compound C is above 50.degree. C. and the boiling point thereof above 200.degree. C. (at 760 mmHg) and ccompound C is capable of at least partially dissolving poly(2,6-dimethyl-1,4-phenylene)ether and is preferably a hydroquinone derivative.