Properties of a unidirectional graphite/epoxy (T300/5208) composite are characterized using tubular specimens. The elastic compliances based on the average invariants are found to describe fairly accurately the elastic behavior under various combined loadings. The equality between the tension and compression compliances and the symmetry of the compliance tensor are also established to within the experimental scatter. The matrix/interface-controlled failure is characterized by a second-order polynomial including a first-order term. This failure criterion agrees with the experimental observation that the compressive loading perpendicular to the fibers can increase the longitudinal shear stress required for failure. (Author)