Costoclavicular syndrome is one of the four syndromes of thoracic outlet syndrome in which have similiar symptoms, and may result from cervical and thoracic scoliosis, formation of excessive callus or nonunion after fractures of clavicle or first rib. Conservative treatment may be offered. Surgical treatment includes scalenectomy with supraclavicular approach, transaxillary first rib resection with scalenectomy and correction of clavicular abnormality. The purpose of this paper is to evaluate the result of surgical intervention in costoclavicular syndrome of a 38-year old man with clavicular nonunion after an operation.