Circadian rhythm abnormalities have been demonstrated in people with depression, including a tendency toward maximal symptom severity in the morning. Although a few studies have suggested that symptoms in people with anxiety are worse later in the day, no detailed study of this observation has been reported. In 86 patients with anxiety disorders (63 with panic disorder or agoraphobia with panic attacks), anxiety symptoms tended to be more severe in the afternoon or evening than in the morning, with no abnormalities of heart rate or oral temperature. This is the first systematic demonstration of a circadian fluctuation of mood in any disorder other than depression.