A composite is a blend of two or more materials that are mixed to gain properties superior to those of the original components. Plastic composites (PCs), also called reinforced plastics, are combinations of a polymer (plastic) matrix and a reinforcing material. Due to their enhanced properties and versatility, PCs are used in nearly all fields of industry. PC may cause both allergic and irritant contact dermatitis. Allergic contact dermatitis is most often caused by thermoset plastic matrices such as epoxy resins. Irritant contact dermatitis is typically caused by reinforcement materials such as glass fiber. Other skin contactants in PC work are, for example, plastic additives, solvents, peroxides, and protective clothing. Clinical investigation of PC-related dermatitis requires careful assessment of the workplace exposures (chemicals and materials) and patch testing the patient accordingly with plastic chemical additives and, when possible, own materials from work.