This study is aimed to evaluate the effect of Cypermethrin on some serum biochemical parameters , body weight and fertility in male rats. A total of thirty albino rats weighing (180 -200g) were used for this study. Rats were divided into 3 groups each of 10 rats. First group was given Cypermethrin 12.5 mg/kg bw. Second group was given Cypermethrin 25 mg/kg bw. and third group was left as control group. All doses were orally administered twice weekly for 65 successive days. At the end of the experimental period, blood samples were collected from each rat for biochemical analysis. Rats were humanely euthanized and testes and epididymis were taken for determination of weight of sexual organs and epididymal sperm characters in male rats. Oral administration of Cypermethrin twice weekly for 63 days in a dose of 12.5 mg/kg b.w. and 25 mg/kg bw. significantly increased the leakage enzymes AST , ALT and ALP. Also increased levels of cholesterol and triglyceride. The effect on the liver is one of the main toxic effects of this product as there was also a significant decrease in the total protein and albumin synthesized by the liver. Cypermethrin exposure resulted in a significant decrease in weight of testis and epididymis, epididymal sperm counts, sperm motility and increase in sperm abnormalities. In conclusion, all these changes were dose dependent, being less with low Cypermethrin dose and more even extensive with high Cypermethrin dose . Also, Cypermethrin has negative effects on hepatorenal cell function. In addition , Cypermethrin has dangerous effect on male fertility due to its effect on spermatogenisis (sperm number, motility and sperm abnormalities).