Background: Ki-67 is a nuclear protein expressed in all proliferating cells of vertebrates during mitotic cycle phases S, G1, G2, and M, except for G0. Studying this marker is widely used to diagnose the proliferative activity of tumors. However, studying Ki-67 in non-neoplastic diseases attracts much less attention among the researchers. The aim of this study was to assess the possibility of using staining for Ki-67 to identify the proliferative potential of fibroblasts during the formation of adhesions in the abdominal cavity (AC). Methods and Results: Experiments were carried out on male Wistar rats. The adhesion process in AC was simulated in the control group (n=25), and in the experimental group (n=25) with the administration of Seroguard®. Animals were sacrificed on Days 1–30, and the severity of the adhesive process in AC was assessed. Histological sections were prepared and stained for Ki-67. It was found that the animals of the control group had increased severity of the adhesive process in AC during the observation. Maximum increase in severity was registered on Day 30 – 12[9-13] points in the control group and 4[4-4] points in the experimental group (P=0.0079). High proliferative activity of fibroblasts in the control group was detected on Days 3, 7, 14 and 30, which may indicate an active division of fibroblasts and the formation of adhesions in the damaged area. In the experimental group, single Ki-67 positive cells were noted during the entire observation period, which may point to a reduced potential for the formation of adhesions. Conclusion: Our study showed the prospects of using Ki-67 staining to determine the severity of the developing adhesive process in AC, and also revealed one of the possible mechanisms that inhibit the formation of the adhesive process when using Seroguard® – a decrease in the mitotic activity of fibroblasts in the area of peritoneal injury.