One hundred thirty-eight impacted mandibular third molars were surgically removed. A prospective study of risk factors associated with the development of alveolar osteitis (dry socket) postoperatively was undertaken. Two surgeons, one experienced and one inexperienced, removed the teeth. Patients were controlled for age, sex, use of oral contraceptives, radiographic difficulty of the extraction, and tobacco use. Patients treated by the inexperienced surgeon and those using tobacco had a significantly greater incidence of alveolar osteitis. Previously identified risk factors of increased age, female sex, oral contraceptive use, and increased surgical time were not associated with an increased incidence of dry socket. Recommendations are made regarding prevention of alveolar osteitis in those patients identified as being at high risk.