Flow induced vibration of tube bundles remains an important problem in the nuclear industry. A number of theories modeling fluidelastic instability have been developed. In those theories, understanding the influence of a tube on its neighbors is of primary importance. Since it is very difficult and time consuming to measure the complete set of cross-coupling effects, numerical simulations could provide a valuable alternative. The main purpose of this paper is to propose the Sensitivity Equation Method (SEM) as a new approach to finding the inter-cylinder coupling effects, which are usually quantified by the derivatives of lift and drag coefficients of all tubes with respect to the coordinates of the reference tube’s location.