Obstructive hematoma is a rare postoperative complication of surgery on the floor of the mouth or the anterior region of the neck and throat. The insidious development of symptoms, including agitation, which may be attributed to other causes, or their late appearance in hospital wards staffed by personnel unaccustomed to treating airway complications, means that the risk of hypoxia or respiratory failure is high. We describe four patients in whom the clinical picture began with agitation and dyspnea. Once the diagnosis was established, and after decompression of the surgical wound, tracheal intubation proved impossible in two patients, who required emergency tracheostomy. Two patients died from lack oxygen. Our review of the literature and experience have led to the following recommendations that may prevent avoidable deaths: a) the caregivers directly responsible for these patients should receive specific training; b) long-term monitoring and observation should take place in recovery units where early signs and symptoms can be detected and treated immediately; c) tracheostomy or 24-hour intubation should be considered when surgery in this anatomic region is highly invasive; d) consider that postoperative agitation in these patients is a symptom of hypoxia unless another cause is demonstrated; and e) the zone must be decompressed rapidly by opening the surgical wound and safeguarding the airway whenever obstructive hematomas present.