Background: The purpose of this study is to analyze the overall survival (OS) of various age groups of patients diagnosed with gastric gastrointestinal stromal tumors (GIST). Methods: We compared 4 different age groups ( < 50 years old, 50-64 years old, 65-79 years old, and 80 or greater) comprising 230 patients in terms of various clinicopathological parameters and OS from January 2010 to December 2020 within Kaiser Permanente Northern California (KPNC), using Kaplan-Meier curves, and Cox proportional hazard regression model. Results: Univariate analysis showed that mitosis greater 10 HPF was a statistically significant predictor of decreased OS from gastric GIST (p = .032). Although necrosis alone was not significant (p = .271), the combination with higher mitotic rate was significant (p = .025). Octogenarians with gastric GIST were more likely to present with bleeding, with a 5.3% ninety-day surgical mortality rate. Multivariate Cox regression showed that patients 80 years of age or greater had decreased OS when compared to the other age groups (p= .002). Conclusions: Gastric GIST mitotic rate is significant in term of overall survival across all age groups and the combination with necrosis portends decreased overall survival. Patients over 80 have a decreased overall survival and require additional vigilance in the early peri-operative period.