ANYONE HAVING the opportunity of studying larger series of chest radiographs invariably encounters variations or abnormalities in the development of the skeleton. These are usually incidental findings. Some, such as cervical ribs, fusion s of vertebral bodies, and cleidocranial dysostosis, may be of clinical importance. Others are without clinical significance, as bifurcated ribs , rib anastomoses, os acromiale, os coracoideum, and appear to be of purely anatomical interest. They are sufficiently described in the roentgenologic and anatomical literature, although without any sat isfactory explanation as to their origin. Such reports of congenital anomalies of the clavicle as have been published deal with more or less extensive defects, ranging from small grooves to complete absence of the bone. No mention could be found in the literature of duplication of th e clavicle. For this reason the following case is reported. E. L. , white male , aged thir ty-four , suffering from deafn ess, bilateral cata ract and bilateral atrophy of the peroneus muscles, following parotitis (final dia gnosis, multiple sclerosis) was referred for x-ray examination of the chest. From th e history it was learned that the patient had been aware of a small painle ss nodule just below the left clavicle as long as he could remember. This was found to be definitely palp able as a subcutaneous structure, freely movable with movements of the shoulder, particularly up and down. With firm pressure upon the skin , th e subcutaneous mass could be moved upward toward the clavicle, indicating free motion, with out attachment to th e latter structure. On manipulation one had a definite sense of palpating the end of a freely movabl e osseous body , which laterally was located deep within the infracl avicular soft tissues. No pain, redness, or swelling was present. Th e overlying skin appeared elevated. No abnormality was noted on the right side. A routine postero-anterior roentgenogram revealed a dense osseous body, approximately 7 X 1 cm., in the region of the left shoulder , just below the clavicle (Fig. 1), which it closely resembled. The lateral end of the bone was somewhat rounded and seemed to be attached to th e coracoid process of the left scapula. The medial end was irr egularly pointed and with out anv osseous connection with the bones of th e immedia'te neighb orhood (clavicle, stern um, or rib s) . Anteroposteri or and oblique views (Fig. 2) showed th e location of thi s bone to be within the anterior soft tissues, about one finger' s width below th e clavicle. Th e medial free end appeared to be widened in an anteroposterior direction, thus being wedge-like in sha pe. A film take n with elevation of th e shoulder girdle exhibited upward movement of th e bone, without any chan ge of th e distance toward the clavicle. Angulation toward the scapula was definitely chan ged, however , suggesting articular connection with th e coracoid process.