Thoracoscopy is performed at best with a rigid apparatus and a cold light source using a single or double site of entry into the chest. Biopsy under direct vision requires a double-spoon biopsy forceps that can be connected to diathermy to insure haemostasis and prevent any air leak age. Some authors prefer a local anaesthesia but a light general anaesthesia with or without intubation allows a safe and painless examination. Numerous biopsies can be obtained for subsequent examinations, like light or electron microscopy, immunofluorescence, bacteriology and mineral studies as well as search for hormonal receptors sites on tumours. Complications are rare and fatalities exceptional (4 cases in a review of the literature covering 3.384 cases. 2 of which occurred in a small series of 150 cases). In chronic pleurisies secondary to cancer, a diagnosis was made in 92% of cases. In suspected pleural mesothelioma, thoracoscopy allows both diagnosis and staging. In pleural tuberculosis, a diagnosis is obtained in 93% of cases. Talc pleurodesis in the treatment of chronic recurrent malignant pleural effusions is successful in 80%. In the treatment of spontaneous pneumothorax with a mean follow up of 10 years, only 6.6% recurred after talc poudrage, and functional sequelae were minimal; no talcomas induced mesotheliomas were seen in a review of 151 cases. Thoracoscopic lung biopsy has an 87 to 94% success rate depending on series, and is thus comparable to surgical biopsy with a markedly smaller morbidity and mortality. It should thus be used more widely by pneumologists.