Isolated submandibular sialadenitis is extremely rare in the neonatal period. All reported cases had predisposing factors such as prematurity, dehydration, anatomic deformities, calculi, and long-term oro-gastric tube feeding. Here, we present a case of neonatal isolated submandibular sialadenitis without any known risk factors and who was diagnosed later with hyperthyroidism secondary to mater...