Persistent undiagnosed fever remains a common problem in clinical practice. In a variable number of cases, no definitive diagnosis is made. This lack of a clear etiology indicates that certain disorders are not being detected despite the recently developed technology usually applied in this situation. On occasion, dental disease is one potential cause of persistent fever. Oral symptoms usually are not present, thus allowing the oral cavity to be overlooked during physical examination. We describe three patients with persistent fever due to dental disease and discuss the pathogenesis of this disease.