Maxillary sinus hypoplasia (MSH) is occasionally encountered in otorhinolaryngological practice. The hypoplastic sinus is liable to mucus retention, and cases of MSH usually present as a persistent maxillary sinusitis. Endoscopic surgery has been recommended as an effective treatment for the sinus infection. However, MSH is associated with anomalies of the lateral nasal wall which, if not recognized pre-operatively, can lead to inadvertent surgical damage to the orbit. Although some of these abnormalities can be evident endoscopically, the role of imaging in diagnosis and identification of important surgical landmarks is paramount. A posteriorly placed middle meatal antrostomy is recommended as the surgical treatment of choice.