AbstractTumours of the appendix are rare and tend to be diagnosed incidentally, in cases of acute appendicitis. For some authors, appendiceal neuroendocrine tumours (ANETs) are the most frequent neoplasm of the appendix, observed in 0.3% to 0.9% of cases acute appendicitis. The present is a unicentric retrospective study conducted between January 2005 and March 2017. Out of a total of 3,007 surgeries for appendiceal pathologies performed in the adult population at the hospital where the present study was conducted, there were 70 (2.33%) malignant cases, 20 (28.6%) of which were ANETs. The patients had a median age of 44 years (range: 18 to 85 years), and were predominantly women (there were 1.9 times more women than men). In 16 cases (80%), a simple appendicectomy was performed (1 patient was submitted to a right hemicolectomy later). The cases of ANETs had a good prognosis in our series: 85% of the patients are either alive today or were alive after 5 years of follow-up. Despite the fact that ANETs are described as the most frequent tumor of the appendix, this was not confirmed in our series, in which they only represented 28.6% of the cases; adenocarcinoma was the most frequent tumor (65.7%) among our sample.