Neuroendocrine neoplasms of the larynx are a rare group of tumors that include carcinoid tumor, atypical carcinoid tumor, and small cell carcinoma. These neoplasms pose interesting diagnostic, prognostic, and therapeutic dilemmas, and they are, as a whole, aggressive tumors with a tendency for local and distant spread. The authors of this study examined six new cases of laryngeal neuroendocrine neoplasms. One case manifested itself as a primary atypical carcinoid tumor and caused a "carcinoid syndrome." The remaining five cases were small cell carcinomas of the larynx. Histologic, immunocytochemical, DNA flow cytometric, and p53 studies were performed on all cases. The expression of neuron-specific enolase and chromogranin were the most useful markers in this group of tumors. Overexpression of p53 protein was present in the majority of cases, including the atypical carcinoid tumor. The implications of these studies for diagnosis, classification, and treatment are discussed.