We have investigated the expression of bcl-2 protein in a panel of small cell lung carcinoma (SCLC) cells lines. Five of six cell lines examined expressed relatively high levels of bcl-2 protein and transcripts. The bcl-2 expression in SCLC cells, however, was not always associated with myc expression. Since dysregulation of bcl-2 may be involved in the course of tumorigenesis and/or in the acquisition of drug resistance of tumor cells, the expression of bcl-2 in SCLC cells may become an important indicator in the prognosis or treatment of SCLC.