Gangliocytic paraganglioma (GP) is an unusual tumor in the wide spectrum of neuroendocrine neoplasms. The biologic behavior and histogenesis of this tumor is uncertain because, despite its benign histologic features, there have been reports of metastases to regional lymph nodes and distant metastases. Although most of these tumors have been reported in the duodenum, examples of GP arising in extra-ampullary sites have been well documented. Herein, we report the case of a lung GP corticotropin producing and presenting as Cushing's syndrome. After removal of the tumor, there was a significant drop in cortisol and corticotropin levels. To our knowledge, this is the first report of a GP causing Cushing's syndrome.