In a sample of 131 patients with panic disorder, we explored both the presence of DSM-III-R criteria for hypochondriasis and the occurrence of illness phobia before the onset of panic disorder. To explore further the possible relationship between hypochondriacal features and panic-agoraphobic syndrome, we compared patients both with and without current hypochondriasis and then patients both with and without illness phobia before the onset of panic disorder. Finally, we investigated the relationship between premorbid phobic-anxious traits and hypochondriasis during panic disorder. No differences were found between patients with and without hypochondriasis, either in terms of clinical features or in the course of panic disorder. Patients with illness phobia before the onset of panic disorder reported higher levels of anticipatory anxiety in nonagoraphobic situations and more depersonalization and derealization during panic attacks, and they met our definition of phobic-anxious temperament more frequently than the rest of the sample. This would suggest that illness phobia before the onset of panic disorder may be viewed either as a separate disorder, a prodrome, or a mild, early-onset form of panic disorder without full-blown attacks. Although patients with premorbid illness phobia are more likely to develop hypochondriasis after the onset of panic disorder, approximately 40% of them do not; therefore, illness phobia should not be considered the only factor that influences the development of hypochondriasis during panic disorder.