Abstract: Objective To investigate the role of Beclin-1 mRNA expression changes in exfoliative cancer cells in predicting the efficacy of introperitoneal cisplatin chemotherapy in gastric cancer patients with malignant ascites. Methods A total of 35 gastric cancer patients with malignant ascites received the treatment of introperitoneal cisplatin (60 mg, Q1W). WHO criteria was employed to evaluate the objective response of chemotherapy, and then patients were divided into objective response (OR) group and no response (NR) group. 20 ml ascties were collected before chemotherapy and 5 days after chemotherapy, respectively; then exfoliative cancer cells were isolated. Beclin-1 and Bcl-2 mRNA expression were detected by RT-PCR. Results There were 54.3% (19/35) cases acquired objective response, mainly with decreased Beclin-1 and Bcl-2 mRNA expression, compared with NR group (P<0.05). Sensitivity and specificity of decreased Beclin-1 mRNA expression in predicting treatment efficacy were 86.7% and 70.0%, respectively. Conclusion Monitoring the changes of Beclin-1 mRNA expression in exfoliative cancer cells may be effective for predicting the short-term effects of introperitoneal cisplatin on gastric cancer patients with malignant ascites.