The effect of the fiber surface treatment on composite material shear behavior is evaluated. The Iosipescu shear test is employed to measure the in-plane shear properties of unidirectional AU4- and AS4-BMI/PES, as well as IM8-BMI/PES with 50%, 100% and 400% fiber surface treatment. In addition, a meso-indentation technique is employed to assess the effect of degrees of surface treatment on interfacial shear strengths. It was found that the in-plane shear properties of AU4- and AS4-BMI/PES laminates are essentially the same. The in-plane shear properties of IM8-BMI/PES laminates with 50%, 100% and 400% fiber surface treatment are approximately the same. Meso-indentation results confirm the Iosipescu shear strengths obtained.