Fluid–structure interaction is analyzed for natural and ventilated partial cavitation of conventional hydrofoils. Quasi-linear two-dimensional (2D) analysis of ideal fluid incompressible flow outside the cavity is coupled with one-dimensional analysis of compressible flows within the cavity and with analysis of hydrofoil bending vibration under impact of periodical oscillations of hydrodynamic forces. The old experimental data for hydrofoils Clark Y-11.7% and NACA 0015 are used for validation of this coupling. Estimations based on obtained computational results show that the force oscillations can be significantly mitigated by ventilation, whereas the ventilation effect on the cavity volume oscillation is less significant. The presented estimations also show that ventilation can suppress generation of shock waves in the cavity tail and affect their propagation.