Because few community surveys of hypochondriasis have been completed, little is known about the epidemiology of this disorder outside of clinical populations. To address this deficiency, the authors obtained information about hypochondriasis and pertinent characteristics from a group of first-degree relatives of hypochondriacal and nonhypochondriacal probands who participated in a family study. In addition to psychiatric diagnoses, the authors elicited information on demographic variables, medical history, impairment in functioning, psychiatric comorbidity, psychiatric symptoms, personality traits, and childhood experiences. The authors identified hypochondriasis in 7.7% of the relatives. These relatives had a high rate of comorbid anxiety, depressive, and somatoform disorders. They also reported substantial physical and psychological impairment, including diminished work performance and disability. In addition, these relatives reported greater utilization of health care but less satisfaction with that care. These relatives showed most of the same characteristics found in earlier studies of hypochondriacal patients.