Apical periodontitis is one of the most common inflammatory conditions of the teeth. Despite the frequent failure of mechanical cleaning as the gold standard, there is still no alternative therapy that would reduce the damage caused by the opening of the pulp and preserve the tooth. The pentadecapeptide BPC 157 has shown great healing potential in various animal studies in many experimental models to date. This study aimed to analyze the effect of pentadecapeptide BPC 157 on a model of apical periodontitis. The treated groups in the therapy received BPC 157 (10ng/kg or 10μg/kg) per os, while the control group drank water during the experiment. Saliva samples and swabs of the oral cavity were collected for microbiological analysis. The damaged tooth and the surrounding tissue were analyzed histologically and molecularly, while the whole experiment was monitored macroscopically and radiologically.Macroscopic observation showed that the remaining coronal part of the tooth tissue around the trepanation opening is more prone to cracking in the non-treated group. Microbiological analysis showed the same count of colonies and bacterial species in all rats. The area of radiographic periapical bone loss and furcation defect was significantly smaller in rats that were taken BPC 157. Histological analysis showed increased levels of inflammatory and cellular patterns in both treated and untreated animals, while a statistically significant difference was found in the number of blood vessels, which was significantly greater in the rat groups treated with BPC 157. Results of RT -qPCR analysis of genes at the mRNA level, in which samples from rat groups treated with BPC 157 were examined and compared with the control group, showed that pentadecapeptide BPC 157 had a significant effect on the expression of the genes of interest. The mRNA expression level for the Egr1 and Ptgs2 genes was < 1 and for the Nos2 and Nos3 genes > 1. This positive effect of BPC 157 opens up opportunities for further research and a novel approach to apical periodontitis treatment.