The middle third of the clavicle is commonly involved in any injury and account for 5-10% of all fractures in adults. Although non-unions are rare, their treatment has not been well defined yet. This report describes the arterial supply of the clavicle to clarify the pathological mechanism and the surgical procedure of non-unions. This study was based on delineation of the thoraco-acromial and suprascapular arteries with colored latex on 17 specimens (ten cadavers). Observations were made after macroscopic dissection and maceration. The main blood supply to the middle third of the clavicle was the periosteal. This supply came from the two branches of the thoraco-acromial trunk that penetrated the pectoralis major muscle and the deltoid muscle. In 13 cases, these two periosteal branches were anastomosed between these two muscle attachments. Periosteal vascularization was always seen on the superior surface and the anterior border of the bone, but never on the inferior surface or the posterior border. The suprascapular artery contributed to supply the middle third of the clavicle by several periosteal branches and also by an independent branch. This branch was born proximally near the internal, middle thirds union and passed along the posterior face of the subclavius muscle and pierced the bone through the nutria foramina located near the external, middle thirds union. Nevertheless, intraosseous arteries were noted only in four cases. In these cases, they were never more than 2cm long. Our results showed that the periosteal blood supply located between the muscles insertions and the arterial supply from the suprascapular artery could be twice compromised in case of important displacement or severe fracture. If treatments of clavicular fractures or non-unions cannot preserve the periosteal blood supply, bone grafting should be indicated.