Machines are usually mounted on seating structures through compliant isolators to reduce the transmission of unwanted machine vibrations. The residual transmission through isolators results from a combination of forces and moments at the contract points. The previous work on transmissions through isolators concentrated on the vertical force induced power transmission. In this paper it is given that a description of the methods for predicting and measuring the moment induced power transmissions. A scries of experiments was carried out on a model system and a full-scale system. Comparisons are made betwcen the results measured using different methods and predicted from a simplified theory to examine the measurement accuracy of each method, and also between the vibrational transmissions induced by vertical force and moments about horizontal axes to examine the character of power transmission through an isolator. It is shown that the moment induced powers transmitted through isolators become important at high frequencies compared with the force induced power transmission, and can be predicted and measured with a reasonable accuracy. Machines are usually mounted on seating structures through compliant isolators to reduce the transmission of isolators results from a combination of forces and moments at the contract points. The previous work on transmissions through isolators concentrated on the vertical force induced power transmission. In this paper it is given that a description of the methods for predicting and measuring the moment induced power transmissions. A scries of experiments was carried out on a model system and a full-scale system. Comparisons are made betwcen the results measured using different methods and predicted from a simplified theory to examine the measurement accuracy of each method, and also between the vibrational transmissions induced by vertical force and moments about horizontal axes to examine the character of power transmission through an isolator. It is shown that the moment induced powers transmitted through isolators beco me important at high frequency compared with the force induced power transmission, and can be predicted and measured with a reasonable accuracy.