Introduction: Oxidative stress and chronic inflammation play an important role in neurodegenerative disease. Flavonoids in citrus peel have antioxidant and antiinflammation activity which contribute as neuroprotective agent. The aim of this study is to determine the effect of citrus peel extract (Citrus reticulata) to hippocampal histopathological in Wistar rats were induced by trimethyltin chloride. Methods: 30 male Wistar rats were divided into five groups those were C1, C2, P1, P2 and P3. The C1 group was administered standard diet. The C2 group was injected intraperitoneally by trimethyltin chloride with a single dose (8 mg/kgBW). P1, P2, and P3 groups were injected intraperitoneally by trimethyltin chloride with a single dose (8 mg/kgBW) and administered orally by citrus peel extract after 48 hours injection of trimethyltin chloride with doses 56.25; 112.5; and 225 mg/kgBW/day until 14th day. On 15th day, samples were terminated and hippocampal tissues were collected for microscopic preparations. Results: The number of degenerative neurons of hippocampus in C2 (35.80 ± 13.084) was significantly higher than P1 (19.20± 9.230; p=0.049), P2 (15.80 ± 4.919; p=0.013) and P3 (19.60 ± 4.929; p=0.032). There was a significant difference of the number of degenerative neurons of hippocampus between C1 (19.40 ± 7.232) and C2 (35.80 ± 13.084; p=0.040). Conclusion: Administration of citrus peel extract (Citrus reticulata) gave an effect for hippocampal histopathological appearances in Wistar rats induced by trimethyltin chloride.