In cases of a pre-operatively diagnosed mediastinal tumour, but with no symptoms of its penetrating the vertebral canal via the intervertebral foramen, and with the surgeon suddenly discovering during anterio-lateral or lateral transpleural thoracotomy the tumor's spur going deep into the intervertebral foramen then it is a modification of the operation involving an effective removal of the mediastinal-intravertebral newgrowth, as described in this report, is most appropriate. This operation is performed in a single-stage fashion both on the level of the thoracic cavity and on that of the vertebral canal by undertaking a through examination of the intervertebral foramen from both sides. The authors believe this modification of the operative intervention to present advantages over the classical Guleke procedure, even in cases with an exactly established diagnosis of neurinoma, when one of its major node lies in the posterior mediastinum and the second--in the vertebral canal. Three cases in which this modification of the operation was applied with success are reported.