Analysis of incidents and near-incidents is an important factor for continuous improvement in patient safety in hospitals and for the promotion of organizational learning. From a system perspective, accidents occur when decision-making at several levels of a working system is faulty and the safety barriers fail. Human error is inevitable but accidents are not. Errors can be used as an opportunity for organizational learning and this is especially true for incidents when patients come to no harm. Starting with explanations of a system perspective on errors, this paper deals with the prerequisites for organizational learning and general rules for establishing incident reporting systems in hospitals.