Purpose Fiberoptic endoscopic evaluation of swallowing (FEES) is a widely used instrumental procedure used to assess swallowing function in persons of all ages, from infants to older adults. In this article, the history of FEES in adults, the protocol, the scoring system, and the interpretation of abnormal findings are summarized. The use of FEES to guide treatment in adults is also covered briefly. Following this review in adults, the use of FEES in infants and children is presented, including the anatomical-physiological assessment and the assessment of swallowing of food and liquid. Interpretation of findings and therapeutic applications are discussed. Conclusion FEES is a valuable part of the clinical protocol for evaluation and management of dysphagia across the life span. It provides a mechanism for in-depth analysis of swallowing structures and function during intake of liquid and food boluses. Future developments include standardized training content to ensure clinical competency and the development of standardized examination and interpretation protocols.