Cervical necrotizing fasciitis (CNF) with thoracic extension is rare. It has never been reported in laryngectomized patients. A case of fatal CNF in a laryngectomized patient equipped with a voice prosthesis is presented. Diagnosis and treatment are discussed. CNF with thoracic extension was diagnosed on clinical picture, computed tomography (CT) and biopsies were taken just above the tracheostoma. Antibiotic treatment was started and extensive debridement of the affected tissues performed. A minor extension to the left pleura was considered irresectable. Irradical debridement and the impossibility of administering hyperbaric oxygen therapy caused death within two day after presentation. CNF is a rare disease and to our knowledge, has never been reported after total laryngectomy. This case emphasizes the need for early antibiotic treatment and radical surgical resection of the affected tissues.