ABSTRACT: Background:Periampullary adenocarcinoma (PAAC) had a poor prognosis, and pancreaticoduodenectomy (PD) remains the only potentially curative treatment. The study aimed to identify the impact of different clinicopathological factors on long-term survival following PD for PAAC. Patients and methods:This study is a retrospective cohort study for the patients who underwent PD for pathologically proven PAAC from January 2010 to January 2019. Statistical analysis was done using Cox regression multivariate analyses for independent risk factors for survival. Result:There were 137 patients with PAAC who underwent PD, 79 patients (57.7%) underwent pylorus-preserving PD. Pancreatico-jejunostomy was done in 108 patients (78.8%). The primary analysis showed that risk factors for poor long-term survival include patients with co-morbidities like hypertension or ischemic heart disease, Carbohydrate Antigen 19-9 > 400U/ml, tumor size > 3 cm, poor tumor differentiation, positive lymph nodes invasion, lymphovascular invasion, and Perineural invasion. Multivariate analysis demonstrated that large tumor size > 3 cm (HR: 0.177, 95%CI: 0.084-0.374, P = 0.002), poorly differentiated tumor (HR: 0.059, 95%CI: 0.020-0.0174, P = 0.016), and perineural invasion in the pathological study (HR: 0.101, 95%CI: 0.046-0.224, P = 0.006) were independent risk factors for poor 5-years survival. The prognosis was better in ampullary adenocarcinoma (5-year survival was 42.1%) than pancreatic adenocarcinoma (5-year survival was 24.3%). The 1, 3, 5 and 7-year overall survival rates were 84.5%, 57.4%, 35.9% and 20.1% respectively. Conclusion:It seems from the current study that Tumor size > 3 cm, poor tumor differentiation, and Perineural invasion were independent predictors of poor survival in patients with PAAC.