Landslide investigations have contributed greatly to enhancing the understanding of slope behaviour in Hong Kong. Insights have been gained from studies of slope failures into the contributory roles of geology and hydrogeology in tropically weathered profiles, which have led to advances in slope engineering practice in Hong Kong. Some pertinent questions are highlighted in respect of landslide risk management vis-à-vis geological, hydrogeological and human uncertainties (i.e. errors or misjudgement). Case studies are presented to illustrate the role of uncertainties in slope failures. Some suggestions are made with a view to enhancing geotechnical and engineering geological input in landslide risk management.