Over the past year, further progress has been made in the determination of the interactions between anaesthetic agents that have been used for a long time and others that have been introduced only recently such as remifentanil. Pharmacodynamically, remifentanil behaves just as the other opioids and interacts with volatile and intravenous anaesthetics as a pure µ-agonist. Substantial effort has been expended in the translation of scientific data that are derived from interaction studies into clinically useful tools. In this way, optimal concentrations have been determined for propofol-opioid combinations that ensure adequate anaesthesia and a rapid recovery.