The present study aimed to study the reproductive effect of Ectomin as pyrethroid insecticide in albino female and male rats as a model of experimental animals and ewes as a model of farm animal. Twenty five male rats were used for male fertility. They were given Ectomin (31 mg/kg .b.wt) for 60 days. Animals were sacrificed every 15 days. Ectomin resulted in a significant decrease in weight of testis, seminal vesicles prostate gland. It also cause a significant decrease in all parameters of male fertility (progressive motility, live sperms and sperm concentration) in addition to significant increase in sperm abnormalities. Histological studies revealed that Ectomin induce testicular dysfunction by inducing clear signs of degenerative changes of the spermatogenic cells, detachment of necrotic cells, desquamation of normal intact spermatocyte and in addition to clear destruction of interstitial tissue. Forty mature albino female rats were used for teratological examination. They were given Ectomin on day 6-15 of gestation (the period of organogenesis). 1-The morphological examination revealed the presence of implantation sites, resorbed foetuses and the living foetuses showed decreased body weight. 2-The visceral examination revealed the presence of cardiomegaly, dilatation of the renal pelvis and hypoplasia of the lung. 3- The skeletal examination revealed the presence of incomplete ossification of the skull, large open fontanelle and absence of sternbrae. Ten ewes were used for hormonal profiles. Ewes were sprayed with Ectomin (1/500 in D.W) during the 1 st day of heat and second spraying was applied 15 days later. The present result revealed that spraying of Barki ewes by Ectomin had no impairment effect neither on the sequencing of estrous cycle nor its length. A significant decrease of P4 (progesterone) was observed on day 9 of estrous cycle (starting of peak level) in the 2nd and 3 rd estrous cycle, and on day 12 of the three estrous cycle followed spraying. On the other hand neither the pattern of gonadotrophins (FSH & LH) nor their levels was affected by Ectomin.