Historically misunderstood to be rare and relatively benign, neuroendocrine tumors (NETs) are increasingly common and are now regarded as malignant neoplasms that can cause debilitating symptoms and potentially life threatening issues for patients. Neuroendocrine tumors are a heterogeneous group of separate clinico-pathological entities that share a common characteristic i.e. expression of endocrine differentiation potential. In the ovary, the term "neuroendocrine" relates mainly to widely-known carcinoids, but it may also be applied to neuroendocrine carcinomas of nonsmall- cell type and small cell carcinomas of pulmonary type. Ovarian carcinoids develop in pure form or in association with other tumors, mainly teratomas. They originate from endocrine cells, either of teratomatous origin or possibly also indigeneous. Ovarian neuroendocrine carcinomas belong most probably to surface epithelial neoplasms, which express endocrine pathway of differentiation. The neuroendocrine carcinomas of non-smallcell type are characterized by the presence of islands, sheets, and trabeculae with little intervening stroma (organoid growth pattern) and cellular homogeneity. However, they are higher-grade than carcinoids. Primary ovarian small cell carcinomas of the pulmonary type do not differ histologically from their counterparts in other organs. They are composed of small cells with scanty cytoplasm and oval to spindleshaped nuclei.