Clinical and physiopathological data about 10 cases of bilateral squamous cell bronchial carcinoma with simultaneous revelation, are reviewed. This clinical form is not rare, usually found by a systematic bilateral endoscopy. In these 10 cases, the clinical and radiological data did not allow to predict the diagnosis before the endoscopy. Physio-pathological mechanisms are not well established. Various hypotheses are propounded : air-way, blood or lymphatic metastases, simultaneous tumoral blossoming, superficial propagation, genetic factors intervention. For these 10 cases, the authors develop arguments for one or another of these mechanisms.