It is important to remember the possibility of nonspecific thoracic outlet syndrome (TOS) when treating patients with neck and upper extremity symptoms. There are no specific diagnostic criteria for the syndrome. Diagnosis is based on symptoms, clinical examination and the ruling out of other causes. The first-line option of clinical care is conservative treatment, which in most cases is sufficient for the patient to regain normal functioning. However, some of the most difficult TOS patients need surgical treatment, especially when persistent symptoms have already begun in adolescence, and if compression of neural or vascular structures is thought to result from anatomical structures. Conservative treatment options are essential also for surgically treated patients.