Abstract: A novel bis-imide matrix resin system comprising 50 to 95 percent by weight of ethylenically unsaturated bis-imides, preferably a low melting mixture of a major portion of maleimides of aromatic amines such as toluene diamine and methylene dianiline with a minor portion of maleimide of an aliphatic amine such as trimethyl hexamethylene diamine and 5 percent to 35 percent by weight of a diunsaturated low-temperature cross-linking agent such as divinyl benzene which gels the bis-imide at low temperatures. This reduces stress between the matrix resin and the surface of the reinforcing fiber, thus reducing the tendency to form microcracks. Room temperature stability is improved by the presence of 0.5 to 5 percent of an oxidation inhibitor such as hydroquinone. The resin is useful as a matrix resin for high performance, graphite fiber reinforced composites.CROSS REFERENCE TO RELATED APPLICATIONThis application is a continuation of Ser. No. 248,978, filed Mar. 30, 1981, now U.S. Pat. No.