Diazinon (DZN) is one of the organophosphorus (OP) insecticides, can affect both animals and man even after exposure to a single dose. Pomegranate molasses (PM), a concentrated pomegranate juice, may be rich in more efficient antioxidants than that found in the juice, but no research has been done on this product. Therefore, the aim of this study was to evaluate the possible protective effect of PM against single half lethal dose of DZN (300mg/Kg b wt) induced adverse effects on contents of Malondialdehyde (MAD) and reduced glutathione (GSH) in rat liver and brain tissues, haematological and some biochemical parameters. Thirty six male albino rats were divided into four groups for ten days as follows: Group1, rats from that group were fed orally with 0.5ml from a corn oil (6 rats). Group (2) rats were injected orally with a single dose of LD50 of DZN (300mg/kg) (12 rats), group (3) rats were given 0.5ml PM plus 0.5ml distilled water / day for 10 days (6 rats), Group (4) animals were given the same single dose of DZN as group plus PM / day for 10 days (12 rats). The results demonstrated that treatment with DZN induced significant increase in MDA and significant decrease in GSH levels in liver and brain tissues. These changes were almost returned to normalcy in rats supplemented with PM +DZN except brain MAD still higher than control group. Red blood corpuscles (RBC) count, hemoglobin (Hb) concentrations and hematocrit (Hct) showed significant reduction, while the value of white blood corpuscles (WBC) count was statistically increased in rats exposed to DZN. Significant increases in the values of serum total protein (TP), globulin (Glob), total cholesterol (TC), triglyceride (TG), urea, uric acid and calcium (Ca) were observed in DZN administrated rats compared to control group. However, PM supplementation together with DZN improved all these alterations except albumin (Alb) and TG significant increased than control group.