Systems with rotating unbalance exhibit vibration of a given amplitude and frequency even below the critical speed of a rotor. The chapter discusses the analysis of a rigid and symmetric rotor supported by slide bearings. The symmetry of the system allows us to consider motion of a single slide bearing only, provided that its length is taken into account twice. Discussions and analyses concentrate usually on examinations of slide bearing systems in terms of their self-excitation which appears after exceeding the critical rotation speed. A rigid rotor system with its in-plane model and hydrodynamic forces are assumed for the considerations. A slide bearing system, such as a viscoelastic one, undoubtedly possesses certain vibroisolating properties preventing or limiting vibration energy transfer to a machine, and ensuring, to some extent, stable motion of the rotor. Computer techniques enabled researchers to develop a qualitative approach toward the study and design process relevant to slide bearings.