Osteoblastic osteitis is a rare kind of bone infection typified by a proliferative reaction of the periosteum and by exuberant bone formation. In the maxillary sinus, it occurs as a consequence of chronic or recurrent sinusitis. It usually manifests with a vague facial discomfort, followed by complications in the deep facial spaces or fossae. The diagnosis is a radiological one. Eradication of this bone infection necessitates removal of the precipitating condition as well as the long-term administration of appropriate anti-biotics. In the case of a deep facial fossae abscess, drainage is mandatory.