Atherosclerosis is caused by an inflammatory process in the endothelium due to an imbalance between oxidant and antioxidant agents that often occurs in Diabetes mellitus (DM) patients. Antioxidants that function to neutralize superoxide can be used to prevent atherosclerosis in DM. Piper crocatum leaves shows an unknown antioxidant effect on the atherosclerosis process.The aim of this study is to determine the effect Piper crocatum leaves extract on blood MDA levels and the severity of atherosclerosis in diabetic rats. 30 Sprague Dawley rats were randomly divided into 6 groups, namely, HC (nondiabetic), NC (diabetic-no therapy), PC (metformin 45 mg/kg), PC200, PC300, PC400 (Piper crocatum leaves extract 200/300/ 400 mg/kg/day). Termination, blood sampling, and histopathological analysis were performed after 14 days of treatment. MDA was measured using the TBARS method, and read on a 532 nm wavelength UV-vis spectrophotometer. The severity of atherosclerosis of the rat carotid artery was observed from tissue stained with Haematoxylin Eosin staining at 400x microscope magnification. The mean blood MDA levels in the PC200, PC300, PC400 groups were 1.24 ± 0.26, 0.85 ± 0.35, 0.10 and ± 0.02, respectively, and a decrease in MDA levels was found in the PC200, PC300, and PC400 compared to group NC. The study showed a decrease in the severity of atherosclerosis in groups PC200, PC300, PC400 compared to groups NC. Piper crocatum leaves extract had an effect on decreasing MDA levels and severity of atherosclerosis in diabetic rats.