From 1940 to September 2008, 21 cases with TDCs extending into respiratory tract have been reported, often with misdiagnosis. There were only 10 cases by the end of 2006, but the number increased rapidly recently. To evaluate endoscopic carbon dioxide (CO(2)) laser procedure for thyroglossal duct cyst (TDC) extending into respiratory tract, we reported an unusual case and performed a retrospective correlate review. A 3-year-old female patient with a TDC extending into respiratory tract, without any neck lumps, was previously misdiagnosed as an epiglottic cyst. An asymptomatic follow-up visit had been for 10 months after she had received endoscopic CO(2) laser procedure. To our best knowledge, endoscopic CO(2) laser procedure was administered for the first time for TDCs, though it had been a valid management of other benign lesions in respiratory tract. The endoscopic CO(2) laser procedure might be for TDC extending into respiratory tract. In order to increase awareness of this situation, we recommend that the novel concept of endogenous type should be considered to unify these TDCs extending into respiratory tract without projecting neck masses.