This article details two case reports and reviews the extant literature concerning acute postoperative submandibular sialadenitis occurring in the side contralateral to the operated site after neurosurgery. Although its precise pathogenesis remains to be elucidated, it is likely related to intraoperative compression of the submandibular gland and surrounding tissues, caused by head positioning and the endotracheal tube. Submandibular swelling rapidly deteriorates after surgery, and emergent airway protection is required in most cases in order to avoid fatal airway obstruction. To avoid serious sequelae, we should be aware of acute submandibular sialadenitis that occurs contralateral to the surgical side, which, although rare, is more probable after posterior fossa surgery. When it occurs, early airway protection is crucial, and the following conservative treatment could provide a good prognosis.