The present study deals with the compressive and flexural creep properties of polyetheretherketone (PEEK), a high temperature semicrystalline thermoplastic. The compressive and flexural modes are important from a practical viewpoint, and yet rather limited viscoelastic data exist presently for testing in the two modes. The creep compli ance results of the unreinforced PEEK and the carbon fiber/PEEK composites are reported for temperatures ranging from 120°C to 160°C. Transverse compressive and cross-ply [±45°]_s flexural compliances, the matrix dominated properties, displayed a significant viscoelastic behavior. The unidirectional 0° samples, on the other hand, displayed only a very limited time dependent response since the composite properties in the longitudinal direction are controlled by the almost elastic response of the fibers. The time-dependent experimental compliance values for the composites are compared to the results predicted from a micromechanics model and the classical lamination theory in conjunction with the quasi-elastic methodology.