Chronic retropharyngeal abscess (RPA) in children is an unusual condition that has rarely been reported in the literature. Pediatric obstructive sleep apnea (OSA) has many etiologies that have been well described, but there have been no reports of a chronic RPA presenting with severe OSA. We describe an infant who presented with severe OSA due to oropharyngeal narrowing by a chronic abscess. An intraoperative magnetic resonance imaging study confirmed the presence of a RPA. Treatment included tracheostomy, surgical drainage, and intravenous followed by oral antibiotics. Physicians evaluating children with recent onset severe OSA after a respiratory infection should include suppurative oropharyngeal pathology in the differential diagnosis. A recent drainage of a head or neck abscess should strengthen that suspicion.