The general methodology for landslide risk management can be applied to rock falls. The uncertainties which affect the failure hazard characterization are described. They explain that the rupture probability is usually estimated in a qualitative way. New approaches are proposed for a quantitative evaluation of rock fall hazard. For a diffuse hazard, failure frequency and impact frequency downslope can be quantified. The failure probability for localized hazards is difficult to estimate. Coupling the classical qualitative geomechanical approach with the frequency based historical approach allows to verify the plausibility of previsions. A quantitative geomechanical approach can be envisaged in some cases where the internal structure of the rock wall is sufficiently known, but it must be associated with an historical one.