Organ failure frequently accompanies the clinical presentations of elderly and adult patients in anesthesia practice. Today, despite the technologically advanced follow-up methods and techniques, organ failures affect the clinical picture of the patient and complicate the follow-up. Perioperative complications increase in anesthesia applications of patients with organ failure. It is important to know the physiological changes and clinical effects of organ failures and to be cautious in order to ensure that the patient is discharged as soon as possible with the least postoperative pain and side effects. Literature information about organ failure, which is very common and important in anesthesia practice, was compiled. In this book, a specific topic was chosen and it was aimed to be useful to practitioners.