Dentigerous cysts are commonly found odontogenic lesions which arise from the crown of impacted, embedded, or unerupted tooth. It is primarily a permanent tooth’s developmentalcyst and is second most common odontogenic cysts after radicular cysts. Dentigerous cysts in association with ectopic teeth within the maxillary sinus are fairly rare, and around 51 cases had been reported in the literature till 2016. In addition to that series, we report a case of dentigerous cyst associated with ectopic canine in the left maxillary sinus. Pathogenesis of ectopic tooth, role of imaging, differential diagnosis, and management will be described here