Background: Gastric cancer with peritoneal carcinomatosis (PC) is considered by most as an end-stage disease. Poor outcomes are achieved with palliative chemotherapy. Aggressive combination of cytroreductive surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) are still debated in this indication. Purpose: to assess the impact of HIPEC on survival and postoperative outcomes after complete CRS compared with CRS alone (CRSa) Methods: Data from 277 consecutive patients treated for gastric cancer with PC in 19 French centers from 1989 to 2014 were collected. 180 patients who underwent CRS and HIPEC were compared to 97 treated by CRSa. Extension of PC was assessed by the Peritoneal Cancer Index (PCI). Only patients treated by complete CRS were included (CC-0 or CC-1). To assess the effect of HIPEC and to account for confounding factors, a Cox proportional hazards regression model with inverse probability of treatment weighting (IPTW) based on propensity score was used. Multivariate models and sensitivity analyses were also performed. Results: After propensity weighting, groups were similar except for the PCI that remained higher in the HIPEC group (median: 6 v 2, P = .003). However, there was no difference in the completeness of CRS (CC-0: 76.7% v 83.5 %, P = .904). HIPEC was associated with improved overall survival (OS) on both multivariate and IPTW models. On IPTW analysis, median OS was 18.8 v 12.1 months. 3- and 5-years OS were 26.21% and 19.87% v 10.82% and 6.43% (HR, 1.66; 95% CI, 1.17-2.37; P = .005). 3- and 5-years disease-free survival were 20.40% and 17.05% v 5.87% and 3.76% (P = .001). Mortality rate (7.4% v 10.1%, P = .820) and grade 3-4 morbidity (53.7% v 55.3%, P = .496) at 90 days were similar. Surgical morbidity was 37.1% v 38.8% in CRSa group. Conclusions: Compared to CRSa, HIPEC was associated with increased OS and potential disease eradication for gastric cancer with PC, without additional morbidity. This treatment, when optimal CRS can be achieved, should be considered as the gold standard since outcomes remain grim with chemotherapies. Clinical trail information: NCT03253939