Background: Gastric cancer patients with malignant ascites often have poor functional status and malnutrition that precludes receipt of systemic therapies. Thus, these patients have a very poor prognosis. Beginning in 2019, our multidisciplinary gastric cancer disease-oriented team implemented a more aggressive supportive care plan for gastric cancer patients with malignant ascites. The initiative included measures such as supplemental enteral nutrition, ascites drainage, and initiation of chemotherapy on an inpatient basis. We compared outcomes for gastric cancer patients who presented with synchronous malignant ascites treated before and after the implementation of the care plan. Methods: We performed a retrospective review of our institutional database to identify patients diagnosed with gastric adenocarcinoma and synchronous malignant ascites between 2010-2022. We compared survival between patients diagnosed from 2010-2018, which will be referred to as the historical control era and patients diagnosed from 2019-2022, which will be called the aggressive supportive care era. Results: 54 patients were included in our analysis; 31 patients were treated in the historical control time frame and 23 patients treated during the aggressive supportive care era. Demographic, clinical, and pathologic characteristics were similar between groups. 3% of historical controls received supplemental tube feeds at diagnosis as compared to 30% of the aggressive supportive care cohort (p=0.008). 3% of historical controls received their first cycle of chemotherapy in the inpatient setting versus 39% of patients treated during the aggressive supportive care era (p=0.001). The median number of chemotherapy cycles received was 5 among historical controls and 9.5 among aggressive supportive care era patients (p = 0.02). There was no difference in the number of days spent as an inpatient between the two groups. The median overall survival for historical control patients was 5.4 months as compared to 10.4 months for patients treated during aggressive supportive care era (p=0.035). Conclusions: Gastric cancer patients with synchronous malignant ascites treated during a timeframe when our multidisciplinary team implemented more aggressive supportive care measures had improved OS as compared to historic controls.Our results suggest that aggressive supportive measures for these patients with highly challenging clinical issues and poor prognosis can prolong survival. Specifically, initiation of chemotherapy in the inpatient setting and supplemental nutrition should be considered for patients at high risk for treatment intolerance.