Background: Alloxan is a toxic chemical which is used for induction of diabetes in experimental animals. In the light of various earlier researches which showed different dosages for induction, it has been decided to select and optimize the correct dosage. Alloxan which is a urea derivative is known for its diabetogenic action and causes damage to β-cells. A histological study is conducted for dosage selection of alloxan causing diabetes.Aims and Objectives: This study strives to establish the correct dose which is 120 mg/kg body weight (b.w) intraperitoneally to Wistar rats. Material and Methods: Male albino rats were procured and grouped as Group 1 (control), and alloxanized groups as Group II: 90 mg/kg b.w, Group III: 120 mg/kg b.w, and Group IV: 150 mg/kg b.w the biochemical parameters like blood glucose, urea, creatinine, uric acid, etc., were determined. Animals were sacrificed and 5 mm pancreatic tissues from various groups were processed for histological examination. Results: Among all, a significant difference in biochemical parameters was observed with 120 mg/kg b.w (Group III) when compared to control group. There was marked degeneration and necrosis in the pancreatic β-cells of islets. Conclusion: Although earlier works have studied the diabetic effect of alloxan, it is pertinent to optimize and standardize the dose selection of alloxan with desirable effects. © 2017 Akella Seshagiri Rao, et al.