A large body of experimental and theoretical flutter results for hydrofoil struts were analyzed to determine significant characteristics. Flutter was found to occur in two different structural mode shapes, corresponding to a predominantly bending mode and a predominantly torsional mode, respectively. The flutter mode shape was related to the vibration mode shapes and the generalized mass ratio of the strut at zero speed. The behavior of the hydroelastic modes of typical struts as a function of speed was investigated by using a strip theory with three-dimensional loading modifications. Flutter predictions for struts which underwent flutter in the torsional mode were usually conservative and predicted the correct mode shape. (Author Modified Abstract)