A total number of 80 Wister male rats, 9 -wk. old were taken, weighed and divided into four experimental groups to investigate the effect of Deltamethrin (DLM) oral administration (0.87, 8.7 and 17.4 mg/kg B.W) for a period of 9 weeks on reproductive organs and fertility indices of Wister male rats. The results indicated that DLM caused a significant reduction in Testis weights, sperm count, motility and viability and fructose in semen. Also induced decreases in serum FSH, LH and Estradiol levels however increase in sperm abnormalities. These results indicated that DLM is a toxic pyrethroid pesticide that produced significant reproductive toxicity in treated male rats as revealed by the severely affected parameters