Idiopathic pretracheal deep neck space infection is an extremely rare condition with potentially devastating complications. We present a series of 3 cases of pretracheal deep neck space infection that arose in the absence of trauma or a congenital lesion and that exhibited mediastinal spread. To the best of our knowledge, these cases represent the first reported series of this rare condition to be published in the English-language literature. All cultures grew Streptococcus milleri, and all patients had a favorable outcome. A high index of suspicion for a deep neck space infection is warranted in view of the devastating complications of this condition. Computed tomography is the investigation of choice. Treatment with intravenous antibiotics and surgical drainage, particularly when mediastinitis is present, is recommended. This rare presentation warrants a thorough investigation to identify the source of infection.