A flow model for analyzing the fluid mechanics of left ventricular-aortic valved conduits has been established. The model is based on a parallel flow circuit analogy of Ohm's law, the classic analysis of Gorlin and Gorlin1 for the determination of valvular areas, and an empirical constant, introduced by Gentle,2 that is descriptive of prosthetic heart valve performance. Favorable comparisons with clinical data indicate that the flow model is capable of predicting volumetric rates of flow through the valved conduit and through the aorta. Applications of the model are discussed in terms of altering the design of the valved conduit to improve its performance. The effect of valvular efficiency on conduit performance is investigated, and it is concluded that the Starr-Edwards ball valve and the Hancock 250 valve offer attractive alternatives if the objective is to increase the volumetric rate of flow through the valved conduit, or to decrease the volumetric rate of flow through the stenotic aortic valve, or both.