Interlaminar fracture toughness GIC were measured using double cantilever beam (DCB) test for mode- I using area method, compliance method, compliance calibration method and modified beam theories. The results showed that epoxy reinforced with random glass fiber has higher GIC (2834 J/m2) than that of epoxy reinforced with woven roving glass fiber (548 J/m2). The results of different types of mid plane layers show that the Interlaminar fracture toughness GIC for [R7//M1/M1//R7]is (3018 J/m2) which is higher than that of [M7//R1/R1//M7] is(354 J/m2) . It was shown also that lay - up...