Chronic osteomyelitis of the jaws presents a diagnostic and therapeutic challenge. A 45-year-old woman presented with episodic pain in the right mandible of two and a half years' duration. During active periods, lasting for 2 to 3 weeks, the pain woke the patient from sleep at a regular time, and had features mimicking a variant of cluster headache. However, clinical, radiologic, and histologic findings confirmed the diagnosis of chronic sclerosing osteomyelitis. Conservative treatment, including 6 weeks of intravenous antibiotics, relieved the pain with no signs of recurrence at the 1-year follow-up. We emphasize the importance of including chronic osteomyelitis in the differential diagnosis of idiopathic orofacial pain disorders, particularly in the mandibular area. Keywords: chronic sclerosing osteomyelitis, osteomyelitis of the jaw, osteosclerosis