Respiratory epithelial adenomatoid hamartoma (REAH) is rare, non-neoplastic lesion characterized by an abnormal proliferation of the glandular part of the respiratory nasal mucosa. Occasionally, this polypoid mass can be bilaterally associated with inflammatory nasal polyps. We present a case of a 63-year-old woman with REAH that originated from the right-sided superior turbinate and that was associated with nasal polyposis of the left nasal cavity. Endoscopic examination results revealed a lobular, yellow, soft-tissue mass in the right nasal cavity and nasal polyps in the left nasal cavity. Therapy included complete excision. Histopathological examination results showed the characteristics of REAH in the right nasal cavity and inflammatory nasal polyps in the left nasal cavity. To our knowledge, only one case of simultaneous presentation of REAH and nasal polyps in opposite sides of the nasal cavity has been previously described. Appropriate cooperation between a rhinologist and pathologist enables a correct diagnosis of these rare and unusual lesions.