BACKGROUND: Advanced gastric cancer with synchronous peritoneal metastases (GC-PM) is associated with a poor prognosis. Although cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is a promising approach, only a limited number of Western studies exist. AIM: To investigate the clinicopathological outcomes of patients who underwent CRS-HIPEC for GC-PM. METHODS: A retrospective analysis of patients with GC-PM was conducted. All patients were seen at the Department of General and Visceral Surgery, Hospital Barmherzige Brüder, Regensburg, Germany between January 2011 and July 2021 and underwent CRS-HIPEC. Preoperative laboratory results, the use of neoadjuvant trastuzumab, and the details of CRS-HIPEC, including peritoneal carcinomatosis index, completeness of cytoreduction, and surgical procedures were recorded. Disease-specific (DSS), and overall survival (OS) of patients were calculated. RESULTS: A total of 73 patients were included in the study. Patients treated with neoadjuvant trastuzumab (n = 5) showed longer DSS (P = 0.0482). Higher white blood cell counts (DSS: P = 0.0433) and carcinoembryonic antigen levels (OS and DSS: P < 0.01), and lower hemoglobin (OS and DSS: P < 0.05) and serum total protein (OS: P = 0.0368) levels were associated with shorter survival. Longer HIPEC duration was associated with more advantageous median survival times [60-min (n = 59): 12.86 mo; 90-min (n = 14): 27.30 mo], but without statistical difference. To obtain additional data from this observation, further separation of the study population was performed. First, propensity score-matched patient pairs (n = 14 in each group) were created. Statistically different DSS was found between patient pairs (hazard ratio = 0.2843; 95% confidence interval: 0.1119-0.7222; P = 0.0082). Second, those patients who were treated with trastuzumab and/or had human epidermal growth factor receptor 2 positivity (median survival: 12.68 mo vs 24.02 mo), or had to undergo the procedure before 2016 (median survival: 12.68 mo vs 27.30 mo; P = 0.0493) were removed from the original study population. CONCLUSION: Based on our experience, CRS-HIPEC is a safe and secure method to improve the survival of advanced GC-PM patients. Prolonged HIPEC duration may serve as a good therapy for these patients.