This research effort has concentrated on methods of analyzing and predicting excessive, unacceptable vibrations of large power plant forced-draft, induced-draft, and booster fans. Such vibrations are currently one of the primary problem areas for power utilities since they cause costly plant shutdowns and, unfortunately, are a relatively common occurrence. A total vibratory system, including supporting soil, foundation, pedestals, lubrication, fan, rotor, housing, motor, etc. , has been utilized in this investigation. A digital computer program was developed to aid in performing dynamic response analyses of such systems. The responses of several existing installations have been determined, satisfactory agreement being obtained between theoretical results and experimental measurements. Overall results of the research study demonstrate that the total vibratory system approach provides a superior means of more confidently analyzing the multi-parameter, fan-foundation-soil interaction problem, and predicting potentially excessive vibrations.