© 2018 Comenius University.AIM: To emphasize the significance of the platelet-to-lymphocyte ratio (PLR) in estimating the postoperative prognosis or survival measures in patients with carcinoma of the ampulla of Vater. METHODS: We retrospectively reviewed 82 patients, who underwent pancreaticoduodenectomy for ampullary carcinoma between July 2001 and April 2014. We investigated the predictive significance of the preoperative PLR for disease-free survival (DFS) or overall survival (OS). The possible correlations between the PLR and clinical or pathological features were also evaluated. RESULTS: The 5-year DFS and OS rates of the patients with carcinoma of the ampulla of Vater after pancreaticoduodenectomy were 51 % and 64 %, respectively. Multivariate analysis revealed a significantly worse OS in patients with a PLR = 212 [hazard ratio (HR): 3.446; 95% confidence interval (CI): 1.4-8.43; p = 0.007], lymphovascular invasion (HR: 2.973; 95% CI: 1.25-7.03; p = 0.013), or pathological stage pT3/4 (HR: 2.761; 95% CI: 1-7.1; p = 0.035). Similarly, DFS was significantly worse in patients with lymphovascular invasion (HR: 2.24; 95% CI: 1.1-4.56; p = 0.025) or stage pT3/4 (HR: 2.243; 95% CI, 1.03-4.84; p = 0.04). CONCLUSION: The preoperative PLR shows a predictive significance for the prognosis of postoperative patients with carcinoma of the ampulla of Vater. We suggest that because of its predictive value, the PLR can be used in the development of further approaches to monitor and manage patients with poor prognosis Tab. 4, Fig. 1, Ref. 45). Text in PDF www.elis.sk.