Minimal pencil realizations of rational matrix functions with symmetries A theory of minimal realizations of rational matrix functions $W(\lambda)$ in the pencil'' form $W(\lambda)=C(\lambda A_1-A_2)^{-1}B$ is developed. In particular, properties of the pencil $\lambda A_1-A_2$ are discussed when $W(\lambda)$ is hermitian on the real line, and when $W(\lambda)$ is hermitian on the unit circle. Categories:93Bxx, 15A23