The aim of the present study was to evalute the protective role effect of lycopene and vitamin E on oxidative stress in Oreochromis niloticus exposed to diazinon (DZN). Adult fish were exposed to two sublethal concentrations (0.76 and 2.3 mg/l) of DZN against the ameliorative effect of lycopene (10 mg/kg) and vitamin E (50 mg/kg) for 14 and 28 days. DZN significantly led to a decline in total antioxidant capacity (TAO). However, lipid peroxidation (LPO), DNA fragmentation percentage, super oxide dismutase (SOD) and catalase (CAT) were significantly increased in gills, liver and kidney from the control values. Also, gills showed the highest accumulated DZN residues. Lycopene (LYC) and Vitamin E (VE) supplementation play an appositive role in detoxification of DZN toxicity. The results suggest that DZN can have effect on the antioxidant and oxidative stress biomarkers of fish negatively. Administration of lycopene and vitamin E could not decrease DZN residues in different tissues, but decreases the toxic effect of diazinon, as well as the decrease of LPO and DNA fragmentation near the control values. Also, TAO, CAT and SOD were better than the groups treated with only DZN.