Background and Objectives: Unlike pancreatic head tumors, little is known about the biological significance of radiographic vessel involvement with pancreatic body/tail adenocarcinoma. We hypothesized radiographic splenic vessel involvement may be an adverse prognostic factor. Methods: All distal pancreatectomies performed for resectable pancreatic adenocarcinoma between 2000 and 2016 were reviewed and clinicopatholgic data were collected, retrospectively. Preoperative computed tomography imaging was re-reviewed and splenic vessel involvement was graded as none, abutment, encasement, or occlusion. Results: Among a total of 71 patients, splenic artery or vein encasement/occlusion was present in 41% (29 of 71) of patients, each. There were no significant differences in tumor size or grade, margin positivity, and perineural or lymphovascular invasion. However, splenic artery encasement/occlusion (P = 0.001) and splenic vein encasement/occlusion (P = 0.038) both correlated with lymph node positivity. Splenic artery encasement was associated with a reduced median overall survival (20 vs 30 months, P = 0.033). Multivariate analysis also showed that splenic artery encasement was an independent risk factor of worse survival (hazard ratio, 2.246; 95% confidence interval, 1.118-4.513; P = 0.023). Conclusion: Patients with cancer of the body or tail of the pancreas presenting with radiographic encasement of the splenic artery, but not the splenic vein, have a poorer prognosis and perhaps should be considered for neoadjuvant therapy before an attempt at curative resection.