The indications and techniques for performing the operation of anterior mediastinotomy are described. In the years 1966-71, 116 anterior mediastinotomies were done. The results of these are presented.In 36 patients the operation was done to provide a histological diagnosis in benign conditions. In 51 patients, with probable carcinoma but normal bronchoscopy, mediastinotomy was done to establish a diagnosis and assess operability; 43 had involved mediastinal nodes proven on histology. In a further 29 patients, with positive bronchoscopic biopsies, mediastinotomy was done to assess operability alone. In all, 14 patients (17-5%) were judged suitable for thoracotomy. Of these, nine had operable disease while five were found to be inoperable.The incidence of complications of the operation was low (11%). These were mostly minor, There were no deaths. Most patients, after anterior mediastinotomy alone, were fit for discharge 48 to 72 hours after the operation.The value of an operation that provides both diagnosis and assessment of mediastinum, lung, and pleura is discussed. The operation of anterior mediastinotomy is compared with mediastinoscopy and, in our opinion, the superiority of the former is demonstrated.In this unit the presence of malignant nodes in the mediastinum is a contraindication to radical surgery for carcinoma of the lung. The place of anterior mediastinotomy to obtain this information and to make diagnoses in obscure lung, pleural, and mediastinal pathology is discussed. It is not proposed to enter the arguments for or against radical or supraradical surgery but rather, with the above criteria in mind, to assess the merits of a minor diagnostic procedure for the prevention of unnecessary thoracotomy with its associated morbidity and discomfort for the patient.In the presence of diagnosed carcinoma of the bronchus, with suspect mediastinal involvement on chest radiography, patients were selected for anterior mediastinotomy only if their general condition and / or bronchoscopic appearance were favourable for lung resection. Eighty-one patients, in the review period, underwent lung resection without mediastinotomy as they had no suggestion of mediastinal involvement on the chest film. Where there was doubt as to the diagnosis mediastinotomy was performed for diagnosis and for assessment for thoracotomy.Carlens (1959)