In this research, polymer blend was prepared from Epoxy resin and unsaturated polyester resin as matrix material (EP/UPE) with weight ratio (90/10) %. E-glass fibers type (woven roven) was used as a reinforcement material with volume fraction for fibers (Vf =30 %) by using hand lay-up method. Some mechanical properties were studied on the specimens of the above mentioned materials and then the results of the blend (EP/UPE) compared with its composite which was reinforced with glass fibers. The samples were immersed in (H2SO4) and (NaOH) solutions with normality (0.1 N) at room temperature for (7,
14, 21, 28) days. The effects of the immersion were noticed on the hardness and impact strength values. It was found that the reinforcement with glass fiber leads to the increasing of both impact strength and shore hardness of the composite before the
immersion. The effects of immersion showed decreasing of hardness values after immersion samples in to both above solutions while the results of impact strength showed an increasing after the immersion in to the acidic solution and decreasing of the pure blend and its composite after the immersion in to the basic solution.