We report three cases of patients with respiratory epithelial adenomatoid hamartoma (REAH) of bilateral olfactory clefts associated with nasal polyposis. REAH is a kind of rare lesion which commonly occurs in nasal cavity, paranasal sinuses, and nasopharynx. Our cases were all localized in bilateral olfactory clefts which is very rare since the most common site reported in the past in nasal cavity is the posterior nasal septum and unilateral. Furthermore, our presented cases all associated with nasal polyposis which can provide greater evidence that inflammation can induce REAH development. Although REAH is benign lesion it can probably continue developing after operation if REAH was not completely resected. So during endoscopic sinus surgery (ESS), complete resection of the lesions is key point in successful treatment of REAH. Although REAH arising from the rhinosinusal region is very rare, rhinolaryngologists should know this entity thoroughly in order to differentiate it from inverted papilloma and adenocarcinoma, since misinterpretation of this lesion may result in aggressive surgery for a benign lesion which could greatly affect patient's quality of life after operation.