Chronic idiopathic hypertrophic osteoarthropathy is a condition occurring predominantly in males at the age of puberty or adolescence and characterized by the osteo-arthropathic syndrome—clubbing of the digits, enlargement of bones and joints, and thickening of the skin of the face—in the absence of any demonstrable primary disease. Its course is slowly progressive to deformity and disability, which are often of extreme degree. The nomenclature has been confounded by the dissimilarity of previous titles in the literature, such as familial acromegaloid osteosis (1, 2), idiopathic familial generalized osteophytosis (3), hypertrophic pulmonary osteo-arthropathy without primary disease (4), and acropachydermia and pachyperiostitis (5). These terms have been used because of certain characteristics of the disease, namely, its familial tendency, superficial resemblance to acromegaly, similarity to other forms of osteo-arthropathy, and the varying prominence of skin or skeletal changes. The history of chronic idiopathic hypertrophic osteo-arthropathy is naturally a part of that of the larger group of osteo-arthropathic conditions. Hypertrophic pulmonary osteo-arthropathy was the name coined by Marie (6) in 1890 in his classical paper to indicate an entity distinct from acromegaly, characterized by clubbed or Hippocratic fingers, arthritic symptoms, and bony thickening, that previously had been unrecognized. It soon became apparent that this syndrome was seen in association with a wide variety of primary disorders, and cases began to appear, also, without evident primary disease. Sternberg (7) in 1899 pointed out that two of Marie's cases, those of the Hagner brothers, which had been sources of controversy since they were first reported twenty-five years previously (8, 9), appeared to constitute a separate group. However, it was not until Oehme (1) in 1919 reported his cases, together with the re-resurrected brothers Hagner, that the condition was recognized as a distinct entity. Oehme noted its relation to puberty and concluded that it was a constitutional disease made apparent by the endocrine imbalance of that period. In the dermatologic literature Grönberg (10) and others (11, 12) described similar cases in which there was marked thickening of the facies. As a rule, these reports attracted little attention, and even the most recent review of the general subject of osteoarthropathy (13), listing 337 references, merely mentioned that idiopathic types exist which are neither hereditary nor undiagnosed secondary types. The entire literature on the subject, except for three scattered reports (3, 5, 14), has appeared in foreign journals. The incidence of the idiopathic form is at best low. In a review of the accessible literature, reports of 21 unquestionable cases of the disease have been found (1–5, 8–11, 14–25); 7 other probable cases (12, 26–30) could not be proved because of incomplete data.