Abstract Cavitation inception in slots on the flat walls is analyzed in the steady flow approach using a viscous-inviscid interaction method. It was assumed that, in the accordance with known observations, cavities appear as spherical bubbles in the cores of vortices near the slot corners. Computed cavitation inception numbers are compared with published experimental results of other authors within wide ranges of inflow parameters. The comparison shows a satisfactory agreement of computations with the measured data.