Garré's osteomyelitis is generally considered to be synonymous with chronic osteomyelitis with proliferative periostitis and occurs most commonly in the first molar region of the mandible. We report a case of Garré's osteomyelitis caused by the infected tooth-germ of a wisdom tooth. A 12-year-old boy had a swelling of the right cheek and his right mandibular second molar was covered by gingiva with pus retention. X-ray examination showed a radiolucent area around the impacted tooth-germ of the wisdom tooth and extracortical new bone at the angle of the mandible. After preoperative treatment with antibiotics, the tooth-germ and extracortical bone were removed. The antibiotics treatment was continued for 18 days postoperation. No recurrence of pain or swelling has been observed thereafter.