The purpose of this study was to evaluate the biochemical, morphometric, and histopathological changes associated with experimental periodontitis in rats in response to local administration of humic acid. Thirty-eight Wistar rats were divided into 5 experimental groups: nonligated (NL) group, ligature-only (LO) group, and ligature + local administration of humic acid (20, 80, and 150 mg/kg body weight per day for 15 days, respectively; L-20, L-80, and L-150 groups). Changes in alveolar bone levels were clinically measured as the distance from the cementoenamel junction to the alveolar bone crest with a stereomicroscope. Tissues were histopathologically examined to assess the osteoclast numbers, osteoblastic activity, and inflammatory cell infiltration among the study groups. Enzyme-linked immunosorbent assay interleukin1β (IL-1β) and IL-10 levels in serum and gingival homogenates were evaluated. At the end of 15 days, the alveolar bone loss was significantly higher in the LO group compared to the NL, L-20, and L-150 groups ( P < .05). The osteoclast number in the LO group was significantly higher than the NL, L-20, and L-150 groups ( P < .05). Inflammatory cell infiltration was significantly higher in the LO and L-80 groups than the other groups ( P < .05). The highest serum and gingival homogenate IL-10 levels were determined in the NL group ( P < .05). The serum and gingival homogenate IL-1β levels in LO group were significantly higher than the NL, L-20, and L-150 groups ( P < .05). Within the limits of this study, it can be suggested that humic acid, when administered locally at 20 and 80 mg/kg doses, may prevent alveolar bone loss in the rat model.