Autonomic and somatic manifestations of anxiety are common in medically ill patients. When anxiety symptoms occur in such patients, the psychiatrist's ability to rapidly identify anxiety and perform a proper differential diagnosis is important, and can be life-saving. For example, a patient with deteriorating cardiac or pulmonary function may be misidentified as primarily "anxious" and referred to the psychiatrist. The change in the patient's medical status is missed until the situation becomes critical. Medication side effects can also cause anxiety symptoms in the medically ill patient. It is important for the psychiatrist to have knowledge of medications commonly associated with such side effects. Diagnosing primary anxiety disorders, such as generalized anxiety disorder, panic disorder, or posttraumatic stress disorder, can be difficult in medically ill patients, but it is an important skill for the consulting psychiatrist. Anxiety can occur secondary to the stress or fear associated with illness, particularly serious illness. This presentation will discuss all of the aforementioned aspects of anxiety in the patient with concomitant medical illness.