OBJECTIVE: Sini decoction is a traditional Chinese medicine used for treatment of cardiovascular diseases. This study aimed to investigate the growth and apoptosis-regulating effects of Sini decoction on human lung adenocarcinoma cell line A549. STUDY DESIGN: The growth and viability of A549 cells treated with Sini decoction were analyzed by observation under microscopy and MTT method. The apoptosis rate of A549 cells was detected by Annexin V-FITC/PI double staining and flow cytometry. Protein levels of Bcl-2, Bax, and caspase-9 were determined by western blotting. RESULTS: Sini decoction significantly inhibited the growth of human lung adenocarcinoma cell A549 and caused significant morphological alterations in A549 cells in a dosage- and duration-dependent manner. The apoptosis rate of A549 cells was significantly increased by Sini decoction treatment and was also positively correlated with rises in Sini decoction concentration and duration. Sini decoction treatment promoted Bax expression in A549 cells but inhibited the expression of Bcl-2. CONCLUSION: Sini decoction inhibits the growth of lung cancer A549 cell growth by promoting cell apoptosis, which might be mediated by regulation of the Bcl-2 protein family. © Science Printers and Publishers, Inc.