The mechanisms governing adhesion are often complicated as adhesion properties depend on several physical and chemical parameters. Owing to the growing importance of adhesion in several fields of research, there are an increasing number of studies in the hope to bring a better understanding of these phenomena. The aim of the present paper is to show the correlation between the surface characteristics of composite materials and adhesion performances of corresponding Surfaces assemblies. To this purpose, surface free energy assessment, roughness measurement, scanning electron microscopy (SEM) analysis, and infra-red Fourier transform (IRFT) coupled with microscopic study have been performed. Relationships between carbon/epoxy and glass/epoxy composite surface characteristics and results from single lap shear tests are established. Conclusions clearly show the importance of considering a polymer composite surface not only as a polymer entity. but also as a fibre/polymer unit.