No wadays, one of the difficulties following the inappropriate ues of drugs is their side effects. These effects are more important in the embryonic period. In the present study we evaluated the teratogenic effects of Acetaminophen on the mice. In the studies done by researchers, almost in no case, definite side effects from this drug ,during pregnancy, have been proved ,however some evidences have been found to show relation between overdose use of Acetaminophen during pregnancy and some fetal abnormalities. In this study we injected pregnant mice intraperitoneally with the different doses of Acetaminophen that are 200,400 and 500 mg/kg a day in the emberyonic period that includes 7th, 8th and 9th day of the pregnancy and we colleced the feotuses in the 19 th day of the pregnancy, then we evaluated their length ,weight and any abnormality and we analyzed the data using statistical tests. Results showed that the average of feotuses length whose mothers were injected with Acetaminophen have been reduced significantly in comparision with the control group but the difference in weight between these two groups was not significant .Also in the group of 500 mg, from 24 cases possessing vaginal plaque only3 pregnancies occurred and in the group of 600 mg despite the vaginal plaque observation ;not only non of the mothers were pregnant but also some of them died Considerig the results of this research ,it is concluded that Acetaminophen can cause some side effects and abnormalities in the mice feotus with different doses.