BACKGROUND Aquafilling® is a soft-tissue filler used in various procedures, including breast plastic surgery. Proponents claim it to be safe and effective without causing serious adverse effects. This study aimed to describe histological changes in breast tissue resulting from potentially harmful effects of Aquafilling®. MATERIAL AND METHODS Tissue samples were collected from 16 patients who underwent surgical removal of Aquafilling®. Histopathological evaluations were performed on hematoxylin and eosin-stained slides, with photographs captured using an Olympus BX 43 light microscope and an XC 30 digital camera at 40×, 100×, and 400× total magnification. RESULTS Inflammatory infiltrates, mainly consisting of macrophages and lymphocytes, were observed in the images. Tissue necrosis was visible in some areas. Fibrosis foci and blood vessels with thickened walls and detached endothelium were identified within mammary adipose tissue. CONCLUSIONS Due to the variety of clinical symptoms and presence of inflammation in all examined women, we recommend histopathological examinations for all cases of Aquafilling® surgical removal. The examination should include information on the extent of inflammation, progression of adipose and muscle tissue damage, and assessment of fibrosis severity. This will help clinicians make informed decisions about Aquafilling® use in patients and improve patient outcomes.