Abstract: his paper describes a preliminary analytical calculation of an extra high-velocity aerated flow made only in the light of the compressibility it exhibits. The aerated flow as a single-phase flow is analyzed by using the conventional continuity and momentum equations,taking into account the effects of flow viscosity and fluctuations. Results of the analysis indicates that in the case of flow past a wall surface with irregularities,very high negative pressures may occur behind the irregularities and that it is impossible to eliminate these pressure even when aeration is provided. As implied above, under such conditions cavitation is unavoidable, on the contrary aeration tends to cause increased negative pressures with increasing Mach nimber, thus no longer playing a role in cavitation inhibition.