The development of non-small cell lung cancer in patients successfully treated for small cell lung cancer has been previously described. Many of these non-small cell tumors appear to be second primary lung tumors. However, the development of second primary small cell lung cancers has not been clearly delineated. In this report, a patient with limited stage small cell lung cancer who had a complete response to chemotherapy plus chest radiotherapy and remained cancer-free for 8 years is described. Small cell lung cancer developed in this patient's contralateral lung with no evidence of recurrence at the original primary site. Clinical evidence suggests that a second primary small cell lung cancer developed in this patient.