The present study aimed to investigate the effect of Carbofuran pesticide on malereproductive organs, semen analysis and thyroid gland in rats. Oral administration of Carbofuran in doses of 4.2 and 10.5 mg/kg. B.Wt. to male rats daily for 65 successive days significantly increased the weight of testes and decreased the weight of prostates and epididymis. Epididymal sperm characters such as sperm motility an concentration were reduced, while sperm abnormalities were increased. The activityof testicular enzymes such as lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and gamma glutamyltransferase (γ-GT) were increased, while the activity ofacid phosphatase was decreased. Carbofuran increased the weight of thyroid gland and plasma level of thyroid stimulating hormones (TSH), while triiodothyronine (T3) and thyroxine (T4) levels were reduced. Biochemical analysis revealed that Carbofuran decreased serum glucose level, AST and ALT enzymes, while total cholesterol was increased. Thus Carbofuran has been shown to induce marked functional changes in male reproductive organs and thyroid gland of rats.