The nonlinear vibrations are considered in a two-degree of freedom rotordynamic system subjected to a bearing clearance effect. The excitation is provided by an out-of-balance within the system, and the nonlinearity, in the form of a discontinuous stiffness, is effected by means of a radial clearance between the elastically supported rotor and the elastically supported outer ring. Different nonlinear dynamics analysis techniques are employed to unveil the global dynamics of the rotor system. In particular the system has been investigated with the help of time trajectories, phase portraits, bifurcation diagrams, Poincare maps, power spectrum analysis and the construction of basins of attraction. A numerical study is presented which encompasses the effects of different system parameters in order to demonstrate the severity of the vibrations. It is also shown that the response of the system can be extremely sensitive to changes in these parameters, and that chaos can exist over large regions of parameter space. (C) 2002 Published by Elsevier Science Ltd.