Vinyl ester resin, or often just vinyl ester, is a resin produced by the etherification of an epoxy resin with acrylic or methacrylic acids. The "vinyl" groups refer to these ester substituents, which are prone to polymerize. The diester product is then dissolved in a reactive solvent, such as styrene, to approximately 35–45 percent content by weight. Polymerization is initiated by free radicals, which are generated by UV-irradiation or peroxides.

In homebuilt airplanes, the Glasair and Glastar kit planes made extensive use of vinyl ester fiberglass-reinforced structures. It is a common resin in the marine industry due to its corrosion resistance and ability to withstand water absorption. Vinyl ester resin is extensively used to manufacture FRP tanks and vessels. For laminating process, vinyl ester is usually initiated with methyl ethyl ketone peroxide. It has greater strength and mechanical properties than polyester and less than epoxy resin.

Vinyl esters provide excellent resistance to water, organic solvents and alkalis, but less resistance to acids than polyesters. Vinyl esters are stronger than polyesters and more resilient than epoxies. Molding conditions for vinyl esters are similar to those for polyesters.

Vinyl ester resins are produced by the reaction ('esterification') between an epoxy resin and an unsaturated monocarboxylic acid. Essentially they comprise a base of polyester resin strengthened with epoxy molecules in the backbone of the molecular chain. Vinyl esters also use peroxides (e.g. MEKP) for hardening.

Vinyl ester has fewer open sites in its molecular chain. This makes it much more resistant to water penetration ('hydrolysis') which can cause osmotic blistering. Vinyl esters shrink less on curing, which means that 'pre-release' of a laminate from a mold is less significant. Vinyl esters are more tolerant of stretching than polyesters. This makes them more able to absorb impact without damage. They are also less likely to show stress cracking.