After having read the articles by Treasure and Beshay about the particular incidence of spontaneous pneumothorax (SP) in patients with daily consumption of Cannabis the authors took a strictly control of these subjects reviewing their personal experience in the treatment of this condition. In particular, the prevalence of SP has been evaluated through genomic assay of monocorial twins. The strong impact of the inflammatory phenomena that have always supported the emphysema burning is 10 time higher among worldwide population and patients with SP.In order to determine the real incidence of spontaneous pneumothorax in patients with proved daily assumption of Cannabis a retrospective analysis of patients with history of Cannabis drug abuse has been performed. In the period from January 2002 and June 2007,12 consecutive patients with SP and history of Cannabis abuse were enrolled. Selection criteria were: 1) age <16 years; 2) single-sided spontaneous pneumothorax; 3) history of daily Cannabis assumption. Patients with previous thoracic surgery/trauma and positive anamnesis for other drug assumption (ODA), snorkelling or work exposition to pollutions were excluded. In order to avoid the clinical overlapping of pathology and clinical symptoms due to other factors, patients with pleural effusion and documented similar episodes were excluded. This series focused on particular on twins. In all the patients an endopleuric drainage tube was inserted, and 3 patients underwent toracostomy.No operatory mortality and/or complications were observed.The role of the thoracic surgeon is important to sensitize on the problem of the circulation of light drugs among young people and their effects on the lung activity.