Data on naturally occurring panic attacks were gathered through continuous self-monitoring for 94 patients suffering from panic disorder with agoraphobia. A total of 1276 panic attacks were collected. In this article various aspects of panic attacks, including severity, duration and time of onset and situations in which panic occurs are addressed. In addition, the symptoms of panic were investigated, examining the (in)variability of attacks within each patient and the patterning of symptoms in the entire group of patients. The most important findings were as follows: attacks occurred predominantly in nonphobic situations; nocturnal panic attacks were generally more severe than attacks during the day; symptom patterns across various attacks, stemming from the same patient, were rather variable; and finally, a substantial number of the attacks (40%) did not meet the DSM-III-R criteria for number of symptoms.