We report the case of a female patient who developed a second contralateral small cell lung carcinoma (SCLC) five years after a right upper lobe SCLC treated by sequential chemotherapy and chest radiation therapy. This second primary neoplasia was revealed by an isolated and symptomatic syndrome of inappropriate antidiuretic hormone secretion. Specific evolution of long-term survivors after SCLC are discussed, including consequences of combined radiochemotherapy and poor prognosis associated with persistence of tobacco smoking exposure.