Abadi SA, Illiyyin Z, Rachmadina JR, Malini DM. 2018. The effect of jengkol (Archidendron pauciflorum) fruit peel ethanolic extract to heart histologic of rat induced by streptozotocin. Biofarmasi J Nat Prod Biochem 16: 59-63. Indonesia is ranked 7th out of 10 countries with the highest diabetic patients in the world. Diabetes mellitus is a disease that can cause heart disorders and adults who suffer from DM are four times more likely to develop heart disease. Jengkol fruit peel has been used traditionally as a drug for diabetes mellitus. The aim of this research was to know the effect of fruit peel ethanolic extract of jengkol (Archidendron pauciflorum) (JFPEE) on rat (Rattus norvegicus) heart histological structure and to obtain effective dose from JFPEE. This research used experimental method in laboratory with Completely Random Design (CRD) using 6 treatments and 4 replications. Treatment was given for 14 consecutive days consisting of negative control, positive control, comparison (glibenclamide dose 10 mg/kg BW), P1, P2, and P3 (JFPEE dose 385, 770, and 1.540 mg/kg BW). Diabetic induction was performed with streptozotocin dose 65 mg/kg BW in female wistar rat except for negative control group. The parameters that observed were number of necrosis and cell damage score, including fat degeneration, hydropic degeneration, and inflammatory cell. The obtained data were analyzed by ANOVA-Tukey's test with 95% confidence level using SPSS version 21 for Windows. The result of histological structure showed that number of necrosis and cell damage score in group of rats treated with JFPEE dose 385 mg/kg BW (174.25±6.34; 1.25±0.50) were not significantly different from the negative control rats (172.00±7.62; 1.00±0.00). The effective dose of JFPEE that can repair the damage of heart cell’s rat induced by streptozotocin was 385 mg/kg BW.