Objective: 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 effects of maternal morphine consumption on brain cavities and central canal development in Wistar rats. Materials and Methods: In this study Wistar rats (average weight: 170-200 g) were used. The experimental group, after pregnancy, received 0.05 mg/ml of morphine by tap water while the control group received water. On the 17th day of pregnancy, the pregnant animals were anesthetized by chloroform and embryos were surgically removed. The samples were fixed in 10% formalin for four weeks. Then, tissues were processed and sectioned. Sections were stained with hematoxylin and eosin (H&E) and examined for ventricle, central canal and choroid plexus development by light microscopy and MOTIC software. Results: Severe reductions of the third and lateral ventricles were observed in the experimental group. In addition, an increase in the choroid plexus (CP) area in the experimental group with regards to the control group was identified. Conclusion: The study showed that oral morphine consumption lead to reduction in the third and lateral brain cavities and an increase in the CP area. This defect may cause behavioral changes observed in the F1 generation from addicted pregnant animals.