Spontaneous Pneumothorax as a complication of lung cancer is rare, as seen from the literature, comprising only 1.13 per cent of all pneumothoraces. All histologic types of lung cancer have been reported principally squamous cell carcinoma probably because of its relatively higher incidence. Beside the fact that it occurs in the same high risk population [Smokers, chronic bronchitis and those with emphysema], pneumothorax may reveal a cancer. Recently, we observed three cases of lung cancer with spontaneous pneumothorax, the one was squamous cell carcinoma and the others were adenocarcinoma. Three cases of spontaneous pneumothoraces occurred as a complication of neoplastic disease.