The anterior mediastinum is the most common site for thoracic tumors in pediatrics. Benignant and malignant lesions include various tumors, most frequently lymphomas. The histological diagnosis obtained by biopsy is the most important determinant for the further treatment. Introduction of a known biopsy method - the Chamberlain procedure in our institution has been commenced as one of the methods for obtaining tissue samples of the anterior mediastinal masses. An anterior mini thoracotomy in the 2nd or 3rd intercostal space gives an excellent approach to the tumor. Three children were operated by this method. The volume of three obtained tissue samples was sufficient for the pathologist and gave a 100% accurate diagnosis. The Chamberlain mini anterior thoracotomy is a good biopsy operative method. It can be used in hospitals which do not have endoscopic thoracic equipment or trained endoscopic surgeons, it is easy to perform and gives comfort to the anaesthesiologist.