A case of osteomyelitis in a 71-year-old woman with paroxysmal nocturnal hemoglobinuria (PNH) is reported. Osteomyelitis of the jaw is a well known condition of the oral and maxillofacial region that may cause severe morbidity. It is well documented that vaso-occlusive crises in sickle cell anaemia, a hemolytic blood disorder, can make the jaw bone susceptible to osteomyelitis. The authors report a case proposing an association between PNH and osteomyelitis of the mandible.