Implantation of blastocyst is considered as a sensitive process in the life of growing embryo. Thus this critical period could be under threat from the harmful effect of many drugs ,among them is the carbamazepine which is used by many women for a treatment of epilepsy . The present experiment was designed to study the effect of this drug on the process of implantation ;especially during the days 7 and 9 of pregnancy. For those purpose 169 pregnant albino mice, of 25 gm weight for each one, were used .The mice were divided into control group given orally normal saline, and treated group given orally carbamazepine with concentration of 15 mg\kg. Samples from pregnant uteri containing the embryos were used. They were first fixed in Boun's solution and 5-8 um paraffin sections were cut to be stained with H and E and one step trichrome stains. The results from control group and treated group have demonstrated that there was no effect of the drug on the process of implantation and the formation of decidual tissue which accompanied the implantation. Both control group and treated groups were showing the same results. In addition to that the blood vessels were well developed at the site of implantation. All these results were signs of success of early period of pregnancy.