Introduction/Aim: Gastric neuroendocrine tumors (GNETs) frequently have an indolent clinical course, despite their metastatic potential. The aim of the study was to identify prognostic factors associated with overall survival and risk of metastases and to evaluate the impact of serial measurements of chromogranin A (CgA). Methods: The authors performed a retrospective cohort study including consecutive patients with GNET diagnosed between 2010 and 2019, with a minimum follow-up of 1 year. Univariate and multivariate analyses were performed. Results: We included 132 patients with GNET (type I, 113 patients; type II, 1 patient; type III, 14 patients; type IV, 2 patients; not classifiable, 2 patients), with 61% being female and a mean age at diagnosis of 66 years. During the follow-up period (median 66 months), 3 (2.3%) patients died due to metastatic disease (1 patient with type III and 2 patients with type IV). Male gender (p = 0.030), type III/IV (p < 0.001), Ki-67 index >20% (p < 0.001), grade 2/3 (p < 0.001), invasion beyond the submucosa (p < 0.001), and presence of metastases (p < 0.001) were identified as risk factors for mortality in the univariate analysis. Metastasis developed in 7 patients (5.3%). Multivariable analysis revealed that Ki-67 >20% (p = 0.016) was an independent risk factor for metastasis. Overall, CgA showed a sensitivity of 20% for detection of recurrence and a specificity of 79% (sensitivity of 8% and specificity of 71% in type I GNETs). Conclusion: Identification of risk factors for the presence of metastases and for mortality in these groups of patients can help in individualizing the therapeutic strategy. CgA seems to be a weak marker for monitoring patients with GNET.