Homalothecium sericeum (Hedw.) Schimp. is growing in habitats such as walls and roofs. It is supported by the studies that moss contains antioxidant, antimicrobial and antitumoral compounds. It was aimed to determine the immunoreactivity of Cu / Zn SOD enzyme in the kidney, adrenal gland, and ovarian tissues of rats due to the increase in the dose of moss extract. In this study, 1 mL of distilled water were given control groups (G1), 50 mg/kg (G2), 100 mg/kg (G3), 300 mg/kg (G4) and 500 mg/kg (G5) moss extract were administered by gavage for 30 days another groups. At the end of the experiment period, the tissues taken from the rats were subjected to routine histopathological procedures. Cu /Z n SOD primary antibody was applied using immunohistochemical staining methods to detect immunoreactivity. The study was terminated by using the Kruskal-Wallis test, which is one of the nonparametric tests. To determine the differences between the groups by evaluating the stained tissue samples with the image analysis system in the light microscope. A significant difference was found in the dose-related positivity of the kidney, ovarian and adrenal gland tissues of the groups given moss extract p. It has been determined that H. sericeum species increases Cu/Zn SOD enzyme activity in the kidney, adrenal gland and ovarian tissues, and its cytotoxic effects shows a dose-related increase in the histopathological table.