In 2003 an anonymous reporting system for critical incidents was implemented in the Department of Anaesthesiology and Intensive Care Medicine of the University Hospital Dresden. This reporting system was modified to an intranet-based version and extended to the intensive care unit (ICU). During the first 18 months 70 anonymous reports originating from the ICU were registered. The most common errors involved fluid management, followed by errors in airway management, cardio-vascular management, neurological problems and errors in drug administration. The main causes were lack of attention, missing check of measures, work load of nurses, experience and communication deficits. The article discusses the incidence of errors in the ICU setting and their potential effects.