A modal analysis technique is developed for dynamic systems with vibration isolation components, e.g. hydraulic or rubber mounts in an engine/mount system, whose dynamic characteristics are represented by frequency-dependent complex stiffness. For such vibration isolation components, mechanics-based transfer function models are employed, whose numerator and denominator are typically polynomials in the complex Laplace operator. The resulting equations of motion of the system are therefore of an order higher than those of a system consisting of constant stiffness, which can be treated by latent value analysis. An engine/mount system is taken to illustrate typical characteristics of dynamic systems with frequency-dependent vibration isolation components by using the developed scheme.