Respiratory epithelial adenomatoid hamartoma (REAH) is a rare benign lesion that affects the nasal cavity and paranasal sinuses. We present 4 cases of REAH that involved the olfactory clefts; 1 case was bilateral. Each of the cases was treated surgically, and no recurrence was observed. Most reports have indicated that REAH occurs in the presence of sinonasal inflammation, particularly nasal polyposis, yet all 4 of our cases occurred in the absence of concurrent rhinosinusitis. This suggests that the etiology of REAH is multifactorial. In addition, we review the literature on REAH, and we discuss its presentation, differential diagnosis, radiology, histopathology, and underlying treatment principles.