This paper presents a novel none-intrusive load and efficiency evaluation method for in-service induction motors based on vibration measurement. The application is in multimotor plants where individual motor monitoring is too expensive yet where motor operational conditions are not accurately determined. The vibration from the motor is detected by an accelerometer and processed by Fast Fourier Transform (FFT) to extract frequencies defining shaft speed and the supply frequency. This data, in conjunction with basic motor performance data enables the actual load and indirectly the efficiency at which the motor is operating to be evaluated. For motors supplied form a variable speed drive (VSD), the loss segregation method is implemented to yield the motor losses indirectly and thus the efficiency of the induction motor.