NOVELTY - Multi-component resin system comprises: (a) a hydroxyl functional unsaturated polyester resin comprising fumaric acid building blocks as unsaturated dicarboxylic acid building blocks and hydroxyl building blocks, and having a hydroxyl value of 40-150 and an acid value of less than 4; (b) an ethylenically unsaturated compound copolymerizable with (a); (c) a polyisocyanate that has on average at least 1.9 isocyanate groups; and (d) a radical initiator, where the molar ratio of cyanate/hydroxyl in the resin system is 2:1-1:50.    USE - The multi-component resin system is useful: in areas of chemical anchoring, construction, roofing, flooring, windmill blades, containers, tanks, pipes, automotive parts or boats; and for producing windmill blades (all claimed).    ADVANTAGE - The multi-component resin system improves mechanical properties and dynamic fatigue properties of glass fiber reinforced laminates.    DETAILED DESCRIPTION - Multi-component resin system comprises: (a) a hydroxyl functional unsaturated polyester resin comprising fumaric acid building blocks as unsaturated dicarboxylic acid building blocks and hydroxyl building blocks having a structure of formula (I), and having a hydroxyl value of 40-150 and an acid value of less than 4; (b) an ethylenically unsaturated compound copolymerizable with (a); (c) a polyisocyanate that has on average at least 1.9 isocyanate groups; and (d) a radical initiator, where the molar ratio of cyanate/hydroxyl in the resin system is 2:1-1:50.    R, R1 = H or CH3 (preferred); and    n+m = greater than or equal to 3, preferably greater than or equal to 4.    INDEPENDENT CLAIMS are included for:    (1) resin composition comprising (A) and (B);    (2) cured objects or structural parts obtained by mixing the components of the multi-component system; and    (3) increasing the dynamic fatigue of a fiber-reinforced composite article prepared by mixing the components of the multi-component system to obtain a mixture, and impregnating fibers with the mixture and allowing the mixture to cure.