Liver resection is a standard surgical procedure and at the moment considered superior to other methods of treatment for primary and secondary liver neoplasm (eg. chemotherapy, radiofrequency ablation, transarterial chemoembolisation, selective hepatic intra-arterial chemotherapy). During liver resection surgery, pathological (afunctional) tissue is surgically removed, in addition to some healthy (functional) liver tissue. Advances in hepatal surgery in recent years have resulted in operative procedures with minimal complications, especially if performed in centers specialized in liver surgery, thus selection of patients suitable for surgical procedure, as well as treatment outcome, depends largely on the extent of resection and function of the remnant liver. Extensive liver resection (eg. 70% resection of living donor liver resection or a smaller percentage in a tumor affected liver, particularly if associated with a diffuse liver illness (eg. hepatitis or cirrhosis) can result in post hepatectomy liver failure (small-for-size syndrome), leading to hepatic decompensation and fatal outcome. Previous studies established that pentadecapeptid BPC 157 can have a positive impact on liver damaged by various toxic agents. The purpose of this study is to establish whether BPC 157 can improve parenchimal regeneration and funcional rescitution of remaining liver. 70% liver resection in rats was chosen as a widely accepted experimental animal model for postresectional liver regeneration. Blood tests and healthy animal sacrificing in order to achieve reference values of analyzed parameters, as well as preresectional measuring of experimental animals for albumin, transaminases, bilirubin and weight of resected lobes were not preformed. Resection was performed on 120 male Wistar rats each with total body mass of 200 gr.. Animals were postoperativly randomly divided into 6 grups (4 BPC and 2 control groups). On postoperative days 4, 14, 21 and 28, five animals from each group were randomly selected for sacrificing (24 groups of five rats in total). BPC 157 was applied (to animals) daily in dosage of 10 μg/kg and 10 ng/kg total body mass, injected intraperitoneally (in 1 ml saline solution) or given perorally (in 12 ml drinking water) respectively, while control group animals recived daily 1ml saline solution intraperitoneally or drinking water only. Just before sacrificing, animals were measured for total body mass and blood samples were taken (measurement of total bilirubin, AST, ALT and albumin). After sacrificing, liver remnant was extirpated and weighted and a tissue sample was taken for patohystological morfometric analysis of hepatocite surface area and nuclei diametar. All resections were made without intraoperative bleeding, postoperative mortality rate was 0% and no ascites were recorded in sacrificed animals. Small data samples lead to use of nonparametric statistics for independent samples and statistically significant difference was calculated with a 5% error. In almost all experimental animals (both BPC treated and untreated) a notable improvement was observed in measured variables and almost all of the animals reached preresectional total body mass (200 gr.) until being sacrificed on postoperative day 14. Analysys of albumin, ALT, AST, bilirubin, hepatocite surface area, also liver remnant mass, total body mass and their ratio, showed that BPC 157 had positive impact on liver remnant and results in better outcome compared to spontaneus liver regeneration (statistically significant difference). The positive BPC impact was already detectable (depending on the variable) in groups of animals sacrificed on postoperative day 4 (AST, albumin, total body mass, hepatocite surface area), as well as in groups of animals sacrificed on postoperative day 14 (ALT, bilirubin, liver remnant mass, liver remnant mass to total body mass ratio) respectively. It should be noted that only in BPC treated animals AST and bilirubin decreased in value (while bilirubin values in control groups kept rising). There was no statistically significant difference in hepatocite nuclei diametar between BPC treated and untreated animals. Additionaly, there was no statistically significant difference in BPC efficiency related either to the way or dosage of application (eg. intraperitoneally, perorally or μg, ng), or to prolonged application time over 21 days. This research suggests that BPC 157 stimulates postresectional liver regeneration in rats, which corresponds to the hepatoprotective effect of BPC 157 found in other studies.