Condensing osteitis of the clavicle, better defined as aseptic enlarging osteosclerosis of the clavicle, is a rare and benign idiopathic lesion. It is probably of degenerative or mechanical origin, and is most commonly seen in middle-aged women as a tender swelling over the medial one-third of the clavicle. Although the clinical features may be confusing and nonspecific, the typical radiographic and histopathological findings will mostly lead to a correct diagnosis of this disorder. The differential diagnosis is quite extensive. Most difficult to differentiate are: avascular necrosis of the medial clavicular epiphysis, sternoclavicular orsteoarthritis, low-grade chronic osteomyelitis, sternocostoclavicular hyperostosis and Tietze's syndrome. The authors recommend a thorough physical examination and technical tests, not only in subjects with pain of the clavicle but also in those with shoulder pain only, especially in women who are in their fourth decade. Treatment with analgesic and anti-inflammatory medications may be variably effective. In refractory cases excisions of the medial one-third of the clavicle may be indicated to offer better relief of symptoms as well as to exclude malignancy.