Multiple-Input Multiple-Output (MIMO) radar offers a lot of advantages and potentials for improving the target detection and parameters estimation performances. Choosing a proper waveform is a critical task for the implementation of MIMO radars. In addition to the general requirements for radar waveforms such as good resolution, low sidelobe level, etc, MIMO radar waveforms also should possess good orthogonality. Unfortunately, we have to remember that the ideal orthogonal MIMO waveform doesn't exist. Realistic MIMO waveforms will always bring some performance degradations, and some trade-offs need to be made in practical MIMO radars. In this talk a brief overview of MIMO radar waveforms are introduced, and some typical realistic MIMO radar waveforms are evaluated and compared for a colocated MIMO radar configuration. The numerical simulation results depict the examples of actual performances (in terms of range/Doppler/angle resolution and sidelobe level) that can be achieved by the realistic MIMO waveforms in practical scenarios.