The results of the mechanical performance evaluation of five types of GRP rods used in NCI are presented. The fractographic characteristics of the rods after exposure to oxalic, nitric and sulfuric acid solutions are also presented. No evidence is found to conclude that the sole action of the acids induce transverse cracking of the rods in a planar mode. Extensive fiber pullout was observed during the mechanical test. The tested rods showed a more marked reduction in their mechanical strength after nitric acid attack. The transverse cracking of the rods in a planar mode which is characteristic of the brittle fracture is found to be dependent on the simultaneous action of mechanical and chemical stresses.