The effect of debonding on various moduli of short fiber composites has been studied by developing an analytical model. It is assumed that debonding of the fiber/matrix interface initiates at the end of fibers, and progresses to the center, as predicted by classical shear-lag theory. Debonding along only a few percent of the fiber length substantially reduces the moduli of the composite material, especially for materials with high volume fractions of reinforcement. Degradation of the bonding can also lead to the growth of preexisting interface imperfections which can add to the deterioration of the material properties. Results are presented for the cases where the fibers are substantially stiffer than the matrix and where the matrix is stiffer than the fibers. It is also observed that a decrease in aspect ratio of the fibers leads to decrease in the moduli of the system in general.