The present study was designed to determine the possible therapeutic effects of oral tomato paste lycopene supplementation on clastogenicity induced by hyperglycemia in diabetic rats. Diabetes was induced by streptozotocin (STZ) injection. Twenty eight male Wistar rats were divided into 4 groups (7 rats per group) as follow: 1-The first group served as control. 2-The second was a diabetic (STZ induced) group, 3-The third was a diabetic+lycopene treated group and 4-The fourth was a lycopene treated group. The treatment period was 2 months and the animals were subjected to micronucleus assay. The results of the present study revealed that a significant increase in micronucleus frequency in the diabetic group (STZ-induced) compared to control. However, supplementation with lycopene in STZ-induced diabetic group decreased significantly the incidence of MN frequency and restores the MN range to the normal control. In conclusion, oral tomato paste lycopene supplementation effectively decreases clastogenicity in Streptozotocin-induced diabetic rats through its antioxidant activity.