Although rock instabilities constitute a threat to human lives and settlements all over the world, methodologies for assessing and zoning rockfall hazards for urban development planning are far from being standardised. After presentation of the general background and classification of existing approaches, the report discusses uncertainties and difficulties which emerge when elaborating hazard maps. It is then underlined how national guidelines condition the hazard zoning and the implications on land use planning. Finally, a new procedure for rockfall hazard zoning is introduced. Starting from 2D or 3D trajectory modelling results, it estimates the hazard level based on a rigorous combination of rockfall energy and return period (according to the strict definition of hazard at the international level).