Remifentanil is a short-acting opioid of high analgetic potency and superior controllability. It is widely used in day-case surgery, procedural sedation, for reduction of recovery-times and obstetrics and whenever excellent controllability of opioid effects is needed. Especially in combination with propofol it is used for target controlled infusion (TCI). The second part of the article shows the differences between groups of patients regarding the use of remifentanil.