Consider a polyhex H which admits a perfect matching M. Harary, Klein and Zivkovic define the perfect matching vector of M as where n_j is the number of hexagons of H containing exactly j edges of M (j=3,2,1,0). Sharp lower and upper bounds on and n₀ for a given H and all M are obtained by mixed-integer programming. Computational experience with polyhexes having over one hundred hexagons is reported.