Treatment of infected mandibular fracture is confronted with various difficult problem, e.g. nosocomial wound infection, non-union of fracture. osteomyelitis. Recently, nosocomial infection has become a major health problem because of excessive morbidity, personal distress, and cost. Frequently, isolated causative microorganisms of nosocomial infection were staphylococcus aureus, pseudomonas aeruginosa, klebsiella species The various manifestation of the disease related to the pathogenesis and the clinical course tend to give a bad prognosis after operation. This is a report of case that post-operative infected mandibular fracture in 53-year-old man was not healed even through aggressive I & D and antibiotic treatment.