Retaining teeth in their proper alignment after orthodontic treatment can be highly challenging. This study aimed to estimate the effectiveness of locally injected chloroquine in improving bone remodeling and reducing post-orthodontic relapse. The third incisors on the right and left lower quadrants of six sheep were removed, and the second and fourth incisors were brought close together by using a sectional orthodontic appliance. Chloroquine solution was injected near and parallel to the mesial surface of the second incisor and the distal surface of the fourth incisor on one quadrant while the other quadrant received 1x phosphate buffered saline as a control. Four weeks later, the orthodontic appliance was debonded and the teeth were allowed to move back. By utilizing digital analysis, the relapse distance of the approximated incisors was measured at 21 and 42 days respectively after appliance removal. Histological and mRNA expression analysis of osteogenic marker (Runx2) were conducted to evaluate the periodontal space width and the new alveolar bone formation of the chloroquine-injected and control sides incisors. clinical and histological measurements showed that the approximated incisors in the chloroquine injected quadrant had a significantly shorter relapse distance (p≤0.05), significantly smaller periodontal ligament width (p≤0.05) and significantly larger new bone area formation (p≤0.05) than in the control quadrant. The mRNA expression level of the osteogenic marker (Runx2) was significantly larger (p≤0.05) in the chloroquine-injected quadrant than in the control quadrant. The outcomes of this research suggest that chloroquine can enhance bone remodeling and reduce post-orthodontic relapse in sheep.