The Internal Combustion engine, by nature a dynamic vibration source, requires a properly designed flexible mounting system to isolate those disturbing vibrations. To do this it is necessary to consider all six degrees of freedom of the engine and to use the computer to determine vibratory outputs for given inputs. An example of such a computer program is given. In addition, the design of a mount system requires consideration of static and dynamic force resistance and reduction, motion limitation, environmental resistance and service life requirements.Elastomeric mounts can provide substantial noise reduction but due to the complexity of the noise problem, the prediction of the actual amount of reduction is more of an art than a science. High frequency problems caused by “standing waves” in an elastomeric mount are very much less likely to occur than those due to structural resonances. Examples of noise reductions due to the addition of elastomer mounts, on some actual vehicles, are given.