Two-phase flow exists in many shell-and-tube heat exchangers such as condensers, evaporators and nuclear steam generators. To avoid flow-induced vibration problems, it is necessary to have some information on tube damping mechanisms.This report pertains to the development of a model to formulate damping in two-phase cross-flow.This formulation is based on information available in the literature and particularly on the results of a recently completed experimental program.The compilation of a data base, the development of a semi-empirical model and the formulation of design guidelines are discussed in this report.The calculation of heat exchanger tube damping in two-phase cross-flow is illustrated by an example.