Osteopetrosis is a rare metabolic disease.1 Dental abnormalities may be attributed to the pathological changes in osteopetrosis. Patients with osteopetrosis are especially susceptible to osteomyelitis of mandible.1 A 13-year-old girl presented with complaint of jaw swelling on left side. The radiograph of left mandible (lateral oblique view) showed small sequestrum with irregularity and erosions of the mandibular cortical margins. This case report aims at diagnosis and treatment of osteopetrosis with superadded mandibular osteomyelitis—a are entity.