In modern anesthesia a variety of volatile anesthetics is available. In cardiac anesthesiology both isoflurane and sevoflurane are frequently used. At present the number of studies comparing the influence of isoflurane and sevoflurane on blood pressure and systemic vascular resistance is limited. Moreover, the results presented in the available literature are inconsistent. The decision as to which of both volatiles should be used during cardiac surgery is not evidence-based, but is based on personal preference of the anesthesist. The most reliable way to compare the effects of isoflurane and sevoflurane on blood pressure and systemic vascular resistance is a randomized controlled trial in patients during Cardiopulmonary bypass (CPB).