Compositions of aromatic polyetherketones and glass and/or carbon fibres

A melt-fabricatable or melt-fabricated composition comprising (i) a crystalline thermoplastic aromatic polyetherketone containing the repeat unit ##STR8## alone or in conjunction with other repeat units, said polyetherketone containing at least 50% molar of the repeat unit I and having an inherent viscosity of at least 0.7 and (ii) at least one of a glass or carbon reinforcing agent, which composition is melt-fabricatable into a composition exhibiting, or melt-fabricated exhibits, an increase in heat deflection temperature, measured according to ASTM D 648, of at least 3.degree. C. per 1% by weight of reinforcing agent in the composition above the heat deflection temperature of the unreinforced polyetherketone, and an increase in flexural modulus, measured according to ASTM D 790, of at least 0.2 GNm.sup.-2 per 1% by weight of reinforcing agent in the composition above the flexural modulus of the unreinforced polyetherketone.