Around 10-20% of sinusitis have a dental etiology. Odontogenic sinusitis is generally caused by periodontitis, peri-implantitis, periapical pathology, or oroantral communication. Ectopic teeth are a rare cause of chronic odontogenic sinusitis. We present a rare case of chronic sinusitis caused by five ectopic teeth.A 39-year-old-female patient presented to our clinic with complaints of facial pain over the left cheek, ipsilateral nasal obstruction, ipsilateral rhinorrhea, and coughing over the last five years. Physical examination revealed a febrile patient. There was an ipsilateral purulent nasal discharge of yellow color. Inspection of the oral cavity revealed the absence of the following maxillary teeth: left first and second premolars, in addition to the left first, second, and third molars. There was also tenderness upon palpation of the left maxillary sinus. Computed tomography (CT) scan of the maxillary sinus revealed hyperdense structures in the left maxillary sinus surrounded by soft tissue, representing the missing premolar and molar teeth. The patient was treated with amoxicillin-clavulanate and corticosteroid, which partially relieved her symptoms.Our case presents an unusual case of chronic sinusitis that was found to be a consequence of five ectopic teeth in the maxillary sinus. A careful physical examination and an appropriate imaging modality are indispensable for the diagnosis of such a rare phenomenon.