Aim. To identify factors related to survival in patients affected by well-differentiated PETs (benign, uncertain behavior, and carcinoma) who underwent R0 pancreatic resection. Methods. Retrospective study of 74 consecutive patients followed up from January 1980 to December 2011. Prognostic factors were sex, age, type of tumor, presence of symptoms, type of surgical procedure, size of tumor, lymph nodes status, WHO classification, and TNM stage. Overall survival was evaluated using the Kaplan-Meier method. Cox regression analyses were used to identify the factors associated with prognosis in univariate and multivariate analysis. Results. The mean follow-up of all the patients was 106 ± 89 months. The 5-10-year long-term survival was 90.9% and 79.1%, respectively. At univariate analysis, patient age <55 years was significantly related to a better long-term survival compared to patients age ≥55 years (307 ± 15 months versus 192 ± 25 months; P = 0.010). Multivariate analysis showed that female gender (P = 0.006), patients without comorbidities (P = 0.033), and patients affected by well-differentiated benign pancreatic endocrine tumors (P = 0.008 and P = 0.002 in relation to tumors with uncertain behavior and carcinomas, resp.) were factors significantly related to a better long-term survival. Conclusions. Patients factors were strongly related to a better long-term survival in patients observed. WHO classification is a very useful prognostic tool for well-differentiated PETs.