Neuroendocrine tumors originate from neuroendocrine cells and occur in a wide spectrum from carcinoid tumors to small cell carcinomas. Although the World Health Organization determined clinical and histological features to predict prognosis for such tumors, they may not be valid on an individual basis. This study investigates the clinical, pathologic and prognostic characteristics of gastroenteropancreatic neuroendocrine tumors that presented to the Medical Oncology Outpatient Clinic, A degrees stanbul University, CerrahpaAYa School of Medicine from 1995 to 2006 (n = 86). The mean age of the patients was 52 +/- A 14 and the male-to-female ratio was 0.87. The most common site of involvement was the stomach. Midgut intestinal tumors seemed to have significant female predominance compared to hindgut intestinal tumors (P = 0.016). Most of the patients had metastatic disease with a prevalence of 34.9%. Poorly differentiated tumors and mixed neuroendocrine carcinomas were significantly larger than 2 cm (P = 0.0001). The median survival was 139 months and the highest mortality was for colorectal tumors (36%). While univariate analysis revealed that the number of lymph nodes (P = 0.008), multiple foci (P = 0.034), metastases (P = 0.022) and stage (P = 0.034) correlated significantly with survival, there was no independent variable in the multivariate analysis. Hindgut tumors had significantly more Ki-67, mitosis and necrosis compared to others (P a parts per thousand currency sign 0.05). In this retrospective study, the clinical, pathologic and prognostic characteristics of gastroenteropancreatic tumors from a single center from Turkey were analyzed and compared with the current medical literature.