SUMMARYA time-integration procedure for dynamic analysis of non-classically damped systems, in which high-frequency modes play a significant role, is suggested. This procedure is an extension of Clough and Mojtahedi's' method. Clough and Mojtahedi suggested integration of the transformed coupled equations of motion where the transformation is done using a truncated set of undamped mode-shapes. The proposed extension consists in adding the response of all the higher modes through a quasistatic analysis. Approximations involved in using such a procedure are examined. Numerical results presented indicate that the proposed extension leads to a significant improvement over Clough and Mojtahedi's method.