Background: 2% to 3% of all living newborns showed at least one recognizable congenital malformation. Monosodium glutamate (MSG) is widely used as flavor enhancer. But, it induces embryonic and fetal toxicity in rats during the gestational periods. Aim of the work: this study aimed to detect the effects of MSG on placenta and fetal developmental stages at 15th and 19th days of gestation. Material and Methods: fifty mature pregnant Albino rats (Weight 200 ± 20 g) were categorized into two groups according to the time of dissection at 15thor 19th days of gestation. From each group, half of the pregnant mothers (G15 and G19)were daily administrated MSG ( 7 g/10mL/kg b. w. by oral)from the 9th to 14th days of gestation). The control groups (C15 and C 19) were received water only. Results: in G15 and G19 groups, the uterine and fetal shape, number of implantation sites, number of living fetuses, body length, fetal and placental weights and the placental co-efficient were negatively changed when compared to the control groups(C15 and C 19). Also, the placental tissue showed congested blood sinuses and large hemorrhagic areas which contained hemolysed blood cells. Some atrophied decidual cells and pyknotic nuclei were observed with highly distorted maternal and fetal placental layers. Conclusions: this study showed that shortterm MSG exposure caused several maternal and fetal changes. Therefore, MSG is considered as embryotoxic agent and the mothers must avoid administration of this substance during the gestation period