Primary neuroendocrine tumours (carcinoid tumours) account for about 4% of anterior mediastinal tumours concerning thymus localization. They appear to have a male predilection (3:1 ratio) and occur mostly between 40 and 60 years of age. Classified primarily as thymomas, they have been considered a different group of thymic neoplasia since 1972. They can be biologically active, mostly associated with MEN -1 (19 -25% of patients and more aggressive in these cases). As a locally invasive disease, with recurrence and metastasis in a high percentage of cases, it correlates with a poor prognosis. Staging is the most important determinant of survival. Encapsulated tumours diagnosed in early stages have an excellent prognosis, while locally invasive tumours in more advanced stages have a relatively poor prognosis as happens with thymomas. Complete surgical removal is the critical factor for long -term survival rates and the basis for treatment of all thymic tumours, independent of histologic type. As an important cause of death, especially in carcinoid tumours associated with MEN -1 and Cushing's syndrome, some authors advocate the need for profilactic thymectomy in these patients.