Between 1991 and 1994 standard cervical mediastinoscopy (SCM) was performed in 22 patients with enlarged middle mediastinal nodes of unknown causes. The pathologic diagnoses were achieved in all patients. Malignancies were found in 45.5% of the patients (10/22) and benign lesions in 54.5% (12/22). An erroneous diagnosis and hence inappropriate treatment were avoided. In our experience correct diagnosis can be made by mediastinoscopy in cases of middle mediastinal nodes enlargement, which is usually impossible by routine examination.