IntroductionThe concept of hypochondriasis, and particularly its nosological position, is far from clear, and there is still a great deal of controversy as to whether or not there exists a condition of primary or essential hypochondriasis. Many of the historical and theoretical ramifications are reviewed in another paper (Kenyon, 1964). The object of the present paper is to give an account of the clinical findings in a large series of patients in order to evaluate some of the hypotheses put forward in the literature, and especially to determine if there is sufficient evidence to delineate a separate group suffering from primary hypochondriasis only. There is a dearth of well-documented case series published, although studies based on the investigation of a group of patients have been made by Gillespie (1928, 1929), Brown (1936), Katzenelbogen (1942), Alarcon (1956), Shirvaikar (1957), Greer (1961) and Ladee (1961). However, none of these attempt any sort of comparison with a “control” series, as is done in the present investigation, nor in most cases are numbers sufficiently large for drawing valid conclusions.