Purpose: This study aimed to evaluate the chemoprevention efficacy of diosmin on experimentally induced hamster buccal pouch (HBP) squamous cell carcinoma utilizing Ki 67 as a proliferative marker. Material and Methods: Seventy Syrian male hamsters were used as experimental animals, these hamsters were divided into five groups, Group I (negative control): 5 hamsters were left untreated. Group II (DMBA treated group): 20 hamsters were divided equally into two subgroups, painted with 0.5% DMBA where subgroup IIa: for 8 weeks while subgroup IIb: for 14 weeks. Group III: 5 hamsters were orally administrated diosmin 150 mg/kg for 14 weeks. Group IV: 20 hamsters were divided equally into two subgroups, treated with diosmin 100mg/kg and DMBA where subgroup IVa: for 8 weeks while subgroup IVb: for 14 weeks. Group V: 20 hamsters were divided equally into two subgroups, treated with diosmin 150mg/kg and DMBA where subgroup Va: for 8 weeks while subgroup Vb: for 14 weeks. Results: Comparing all groups and subgroups revealed that the mean values have been arranged with the following descending pattern subgroup IIa, subgroup Va, subgroup IIb, subgroup Vb, subgroup IVb, subgroup IVa, group III and group I. ANOVA test revealed a statistically significant difference between groups. Conclusion: Diosmin 100mg/kg is considered a promising chemopreventive agent in preventing induced HBP squamous cell carcinoma.