Background: VTE is a largely preventable leading cause of mortality among patients with cancer. Gastric cancer (GC) is one of the most pro-thrombotic solid tumors. The use of effective prophylaxis for cancer-associated thrombosis CAT is anchored on reliable VTE risk stratification. Pre-chemotherapy lymphocytes (PCL) are associated with both arterial and venous thrombosis and play an important role in the thrombogenic pathway; however, their clinical significance in GC CAT is unknown. Aim: To test PCL as a predictor of VTE in patients with gastric cancer Methods: Single institution chart review of GC treated patients (2010-15). VTE events were objectively confirmed in all cases by imaging. Active cancer was defined as biopsy positive metastatic disease or on chemotherapy. Demographic variables, PCL and potential confounding variables were independently extracted. We present continuous variables as median (interquartile range). Categorical variables are expressed as percentages. SPSS version 23 was used and Chi-square, Mann-Whitney U, and logistic regression with forward modeling were applied. Results: We included 112 patients in the analysis who were 58 (51-64) year-old, predominantly male (66%), with adenocarcinoma (84%), and advanced disease (59%). The follow-up was 21.3 months (9.5 - 42.6). VTE occurred in 13 (12%) patients: 4 extremity, 4 splanchnic and 5 pulmonary embolisms. Median PCL was 1.6 (1.0 - 2.1). We selected PLC > 1.75 as optimal cutoff based on the ROC performance for new VTE (sensitivity of 70% and specificity of 67%). PCL >1.75 was an independent predictor of VTE (OR: 4.9; 95%CI: 1.3-18.1; p=0.02) after adjusting for body mass index, performance status and cancer stage. Conclusion: PCL independently predicted VTE occurrence among patients with GC. Pending external validation, PCL could be implemented in risk stratification strategies specific to GC thromboprophylaxis