Objective - The purpose of this study was to assess the bacteriological response in alveolitis in rats treated with the homeopathic medicine Merc solubilis (Merc sol.) 12 cH.Methods - The study was randomized and observer blind. The animals were anesthetized and the upper right incisor extracted resulting in alveolitis. Animals were randomly assigned to groups (n = 18/group): Water control, Alcohol control and Merc sol. 12 cH. These groups were subsequently divided into 3 subgroups (n = 6/subgroup): Early Euthanasia (EE), Mid Euthanasia (ME) and Late Euthanasia (LE), killed at the 6th, 15th and 21st days respectively. The perialveolar microbiota was collected by swab in Brain Heart Infusion (BHI) for seeding and bacterioscopy. After seeding, the Petri dishes were incubated at 37°C for 48 h.Results - Quantitative and qualitative changes were observed in the perialveolar microbiota when the groups were compared. Water control and Alcohol control had the highest counts of pathogenic bacteria, the microbiotica of the Merc sol. group remained closer to normal.Conclusions - Merc sol. 12 cH did not reduce bacterial growth, but the microbiotica remained within the parameters of normality, obtaining the best results at 21 days after treatment.