This book, part of the European Society of Intensive Care Medicine (ESICM) textbook series, provides detailed up-to-date information on the care of the critical ill very old (=80 years) patients in the ICU. The very old are expanding fast in our populations, and this is mirrored in our hospitals and ICUs as well. During the last decade, a lot more information about the group of critical ill elderly has been published, and several large networks cooperate in performing multinational studies in this field, one of them with roots in the ESICM. This book will give readers knowledge about the current epidemiology of elderly ICU patients, in  patients centered outcomes and factors affecting these outcomes. A large part is devoted to age related changes in vital organ functions, and the specific geriatric “syndromes” like frailty, cognitive decline, reduced activity of daily living, sarcopenia and immunosenecence. This is all important for the practicing intensivists to know about. In addition, specific groups of the elderly in the ICU are also described like the elderly patients with trauma or sepsis. The book is written jointly by intensivists and geriatricians, often working in teams and originating from many different countries. This herald a new era in the collaboration between these two groups in order to improve care and rehabilitation. We have a lot to learn from each other, as both groups have a holistic view of our patients although with different perspectives. This book should be of value for all working in adult ICUs, physicians as well as nurses. It will hopefully lead to a better understanding of the particular challenges posed by this important sub-group of ICU patients and how to manage his group in a way that combine respect for life as well as death and includes patients and caregivers in this process.