Chronic osteomyelitis of the mandible is an infrequently reported condition, but recent experience with six cases over a 14-month period suggests it is more common than appreciated. Chronic mandibular osteomyelitis results from odontogenic infection, postextraction complication, trauma, or irradiation to the mandible. Clinical findings include local pain and swelling and trismus, but constitutional symptoms are unusual. Radiologic examination discloses radiolucent areas, bony destruction, and sequestrum formation. Pathogenic organisms are normal oral flora, Staphylococcus aureus, and aerobic gram-negative bacilli. Chronic mandibular osteomyelitis must be differentiated from malignant disease involving the mandible. Diagnosis is accomplished by bone biopsy and culture. Treatment involves through surgical debridement and prolonged antimicrobial therapy. Osteoradionecrosis of the mandible is extremely recalcitrant to conventional therapy, but aggressive surgery and treatment have proven effective.