The records of 1,371 patients with small cell carcinoma of the lung (SCLC) treated between 1983 and 1994, were reviewed for the occurrence of second primary malignancies (SPM). One was excluded for analysis because of insufficient data. Eight synchronous SPM (SSPM) and 8 metachronous SPM (MSPM) were identified, SSPM included non-small cell lung cancer in 6 patients, 1 head and neck cancer and 1 oesophageal cancer. Median survival after the diagnosis of SSPM was 6 months. The MSPM were detected between 1 and 6 years after the diagnosis of SCLC. MSPM included lung cancer (3 patients), gastrointestinal malignancies (2 patients), 1 hematologic malignancy, 1 prostatic cancer and 1 head and neck cancer. The median survival time after the diagnosis of MSPM was 4 months. Occurrence of SPM is a singular pattern of patients with SCLC. Tobacco consumption, genetic factors and carcinogenic effects of multimodality treatment are supposed mechanisms to explain SPM.