Due to the anatomical location, vallecular cyst is a rare but well-recognized cause of upper airway obstruction and death in newborn. This cyst can be accurately diagnosed by echography in utero and by MR imaging. Prenatal diagnosis allows for early consultation with surgical specialist, so that the time and place of the delivery can be addressed for neonatal preoperative planning. We report the first prenatal diagnosis of a vallecular cyst at 25 weeks of gestation. At birth, the cyst was drained and then marsupialized. We believed that, in cases of oropharyngeal tumors discovered in utero, elective delivery should be realised in a tertiary referral center in which emergency ventilation and tracheostomy are possible.