In some surgical patients immunosuppression is easily apparent and directly caused by known underlying disease or treatment. In others, although induced by the underlying disease, immunosuppression may be less obvious. Perioperative management of immunocompromised patient is mostly directed by the fact that immunosuppression itself does not cause pathology, but does leave the patient prone to infection. Immunodeficiency can be broadly characterized as congenital (primary) or acquired (secondary). The majority of immune deficiencies that are of interest to the anaesthetist are acquired. They can be present both in children and adults, in a huge variety of patients that are presented preoperatively. Most of them do not require different than usual perioperative anaesthetic management. However, in some of them specific aspects of treatment should be considered, such as HIV infected, cancer, transplant patients, and those scheduled for organ transplantation.