Indonesia is among the top 10 countries in the number of diabetes today. Oxidative stress plays an important role in the progression of diabetes, so that the use of antioxidant in diabetics can be beneficial. Antioxidant needed to stop the oxidative stress, one of which is a phenolic compunds. Phenolic compounds can be found in the roots of plants Simpur (Dillenia suffruticossa). The roots of this plant contain high levels of phenolic compounds is very high. This study is required to determine the effect simpur root extract to diabetic rats pancreatic histopathology. The research model is carried out purely experimental post test and the controlled group design in test animals. Number of samples of each group in this study were 5 rats (n≥4) and there are six treatment groups. This study used 30 rats and conducted over 30 days. Analysis of the amount and size of the island of Langerhans of the pancreas using Kruskal-Wallis test to assess differences in all groups, followed Mann-Whitney test to assess differences between groups. DS extract treatment 2mg / 200grBB showed a significant difference to the negative control, positive control and extract treatment DS 0.5mg / 200grBB. These results indicate that the extract treatment DS 2mg / 200grBB able to minimize the damage of the pancreas demonstrated by the number of pancreatic islands Langherhans more than the negative control. However, treatment DS 2mg / 200grBB not differ significantly to the negative control in terms of the size of the island Langherhans in statictic. Award Simpur Root Extract (Dillenia suffruticosa) dose of 2mg / 200grBB STZ induced diabetic rats were able to minimize damage to the pancreas Langherhans island in terms of numbers. However, the provision Simpur Root Extract (Dillenia suffruticosa) all dose STZ induced diabetic mice have not been able to minimize the damage to the pancreas Langherhans island in terms of breadth.