Background: Cytoreductive surgery (CRS) followed by hyperthermic intraperitoneal chemotherapy (HIPEC) can improve prognosis of patients with peritoneal metastases (PM) in colorectal cancer. In gastric cancer (GC) patients with PM this concept is under debate. Perioperative chemotherapy has been shown to improve survival in gastric cancer. In patients with limited PM systemic chemotherapy, a palliative gastrectomy and CRS may prolong survival compared to chemotherapy alone (Sun) in selected patients. It is unclear whether HIPEC has an additional benefit in this setting. The GASTRIPEC trial (NCT02158988) will clarify the role of HIPEC. Methods: It is an open label, multicenter randomized phase III trial. 180 patients with histological proven GC or GE-junction and PM will be included. All patients will receive 3 cycles of pre- and postoperative chemotherapy, dependent on the HER 2 status (Her 2 + ve: cisplatin, capecitabine, trastuzumab (CCT); HER 2 –ve: epirubicin, oxaliplatin, capecitabine (EOX). All patients will receive gastrectomy and peritonectomy. Patients randomized into group B will be treated with additional intraoperative HIPEC with Mitomycin C and Cisplatin for 60 minutes at 41-43°C. Main inclusion criteria: Histological proven PM in GC including adenocarcinoma of the GE-junction, no evidence of distant metastases in CT scan chest and abdomen other than PM (exception of Krukenberg tumors), estimation of peritoneal cancer index via staging laparoscopy or laparotomy, possibility of 80% tumor reduction at CRS, Karnofsky lndex > 70%, written informed consent. We hypothesize a hazard ratio for overall survival as the primary endpoint of 0.65 (9 months in None-HIPEC versus 13.8 months in HIPEC arm). With an alpha error of 0.05 and a power of 80 percent 180 patients need to be enrolled. Secondary endpoints are 30 days complication-rate, time to progression, quality of life, toxicity, adverse events. 18 patients are included since March 2014. Conclusion: The GASTRIPEC trial may help to clarify the role of HIPEC in addition to systemic chemotherapy, gastrectomy and CRS in GC patients with limited PM. Clinical trial information: NCT02158988