The purpose of this study is to assess the incidence of symptomatic and asymptomatic venous thromboembolism (VTE) and their prognostic effect on survival in patients with gastric cancer. A total of 201 VTE cases from 1420 eligible patients with gastric cancer were enrolled in this study. VTE events were divided into two groups as symptomatic or asymptomatic according to the symptomatology of thrombosis. Trombus Overall Survival (TOS) was defined as the period between the date of VTE diagnosis and the date of death or the date of last visit of patient. Of these 201 VTE cases, 101 were symptomatic. Metastatic period (61.7%) and the first 6 months (67.7%) after the cancer diagnosis were associated with the highest incidence of VIE. Extremity (97.7%), port-related (100%) and pulmonary (59.7%) thrombosis were found to be clinically symptomatic, while visceral thrombosis (97.3%) were mostly asymptomatic. TOS for stage I-III patients with symptomatic VTE was found to be 26.4 months in comparison to 33.2 months for those with asymptomatic VTE (p= 0.29).TOS for symptomatic and asymptomatic groups with metastatic disease were 3.4 months and 6 months, respectively (p= 0.01). In multivariate analysis of metastatic patients, symptomatic thrombosis was statistically significant factor for poor TOS. In conslusion, metastatic stage and first 6 months after cancer diagnosis are the crucial periods in which the thrombosis mostly occurs. Although symptomatic thrombosis in patients with metastatic gastric cancer had an adverse prognostic effect, asymptomatic VTE had no significant impact on the prognosis, hence asymptomatic VTE may be followed without anticoagulant therapy.