Considering the increasing prevalence of alcohol use and the growing number of orthodontic patients, some orthodontic patients might engage in binge drinking along the treatment. Nevertheless, little is known about the effect of alcohol use on orthodontic treatment. Male Wistar rats were divided into ethanol and control groups (n = 32). The rat received a single daily intraperitoneal injection of 20%(vol./vol.) ethanol/saline solution at a dose of 3g/kg or saline for 3 consecutive days, and no injection was given during the remaining 4 days each week. All rats received orthodontic appliances to draw the maxillary first molar mesially. The rats were sacrificed at days 14 and 28, respectively. The amount of tooth movement was measured. Root resorption area was evaluated by scanning electron microscope. The hematoxylin and eosin (H&E) staining and tartrate-resistant acid phosphatase (TRAP) staining were conducted. Immunohistochemistry staining was performed to evaluate the expressions of nuclear factor kappa B ligand (RANKL), osteoprotegerin (OPG) and inducible nitric oxide synthase (iNOS). There were no significant differences in tooth movement and root resorption between ethanol and control groups. The number of TRAP-positive cells was significantly higher in ethanol group. The expression of RANKL was statistically increased in ethanol group. In contrast, the expression of OPG was remarkably decreased in rats injected with ethanol. Moreover, the iNOS level was significantly up-regulated in ethanol group.