We present an algorithm for computing the pole-zero representation of descriptor systems whose generalized state-space models are described by the 5-tuple (E, A, b, c. d), where E may be a singular matrix but del (A - λE) ≠ 0. The proposed algorithm uses only-orthogonal transformations; hence the computed results are numerically reliable. Numerical examples are included to illustrate the proposed results. © 1995.