Background: Heparin has been widely used to prevent cancer-associated thromboembolism in cancer patients. Recent evidence reveals that heparin could modulate cell proliferation in the stomach. The effect of heparin on gastric cancer growth, however, is unknown. The effect of heparin on the proliferation of a human gastric adenocarcinoma cell line, BGC-823, was investigated. Materials and Methods: Cell proliferation was assessed by [3H]- thymidine incorporation. The expressions of several growth-related genes were determined by RT-PCR and Western blot. Results: Heparin significantly increased cell proliferation in BGC-823 cancer cells by 15.5% at the dose of 0.2 μg/ml. Heparin also up-regulated c-Myc protein expression by 14.4%. In contrast, mRNA and protein levels of epidermal growth factor receptor (EGFR) were, respectively, down-regulated by 12.7% and 8.2% with no effect on cyclooxygenase-2 mRNA or protein expression. Conclusion: Our results suggest that heparin can promote the proliferation and up-regulation of c-Myc protein expression in gastric cancer cells.link_to_subscribed_fulltex