Series and parallel bimaterial composites were constructed by injecting C fiber poly(ether ether ketone) (PEEK) into a mold containing a fraction of a previously molded polycarbonate (PC) dogbone. Resulting specimens were tested in tension. For series composites, breaking stresses were independent of fractional length. However, elongation to break decreased with fractional length of C fiber PEEK and apparent stiffness increased. On the other hand, for parallel composites, breaking strains were independent of the fractional cross-sectional area, while breaking stress and stiffness increased with the C fiber PEEK fraction. (C) 2000 John Wiley & Sons, Inc.