Introduction: Previous studies have shown that morphine consumption during pregnancy may delay embryo development or cause abnormal nervous system function. The present study focused on the effect of maternal morphine consumption on development of maternal and fetal portion of placenta and blood corticosteron concentration in addictive pregnant mother. Materials and Methods: In this research, 24 female Wister rats, 170-200 g weight, were used. The experimental groups after pregnancy received an oral dose of 0.05 mg/ml of morphine by tap water while the control group received tap water. On 10th and 14th day of pregnancy, Wister rats were anesthetized by chloroform, and placenta with uterus removed surgically, 1 ml blood was collected from each pregnant mother from Retro-orbital sinus, and the concentration of blood corticosteron was determined by corticosteron Elisa kit after centrifugation. The fixed tissue processing, sectioning and staining with hematoxylin and eosin. Placenta was studied microscopically according to the thickness of layers, area of blood cisterns, and the number of cells.Results: Comparing the plasma corticosteron concentration of the treatment and the control groups, not only a severe increase in the treatment group was detected, but also the thickness of maternal and embryonic portions of the placenta at day 10th and 14th of gestation (pregnant) was different significantly (p=0.05). Furthermore, an increase in number of cells in maternal and embryonic portion of placenta and a decrease in blood cistern area were demonstrated in both the experimental and the control groups.Conclusion: The effects of morphine, including an increase in blood concentration of corticosteron, in dependent pregnant mothers were seen. Development of placenta in the experimental group was delayed.