The properties of the fiber/matrix interface in carbon fiber-reinforced composites play a dominant role in governing the overall performance of the composite materials. Understanding the surface characteristics of carbon fibers is a requirement for optimizing the fiber-matrix interfacial bond and for modifying fiber surfaces properly. Therefore, a variety of techniques for the surface treatment of carbon fibers have been developed to improve fiber-matrix adhesion as well as to enhance the processability and handling of these fibers. Many research groups have studied the effects of plasma treatments, correlating changes in surface chemistry with the interfacial shear strength. This article reviews the recent developments relative to the plasma surface modification of carbon fibers.