Abstract: Objective To investigate the effect of di-(2-ethylexyl)phthalate(DEHP)on embryoim plantation in early pregnancy and fetus development during medium and late pregnancy in rat.Methods DEHP was admin istered to pregnant rats at 5,25,50 mg/kg from 1 to 6 days of pregnancy,and other pregnant rats were given DEHP from 7 to 20 days of pregnancy.The pregnant rats were killed on 14th or 21st day of pregnancy.The embry omiplantation cases,food in take and body weight of female rats,the weight of fetal body and placenta,the number of live fetuses,the number of dead fetuses,and the number of absorbed fetuses and fetalmal formations case for the rats were observed.Results In early pregnancy,embryo miplantation cases in DEHP groups of mode rate-and high-dose(10.02±2.75,8.77±3.03)were lower than that of in the control group(14.01±3.01).In middle and late pregnancy,the cases of live fetuses in moderate-and high-dose DEHP groups (9.68±1.95,5.86±2.11)were lower than that of in the control group(12.98±1.46).Live birth cases in moderate-and high-dose DEHP groups(8.29±2.02,5.86±2.21)were lower than that of in the control group(12.13±2.06).The weight of fetal body and placenta in moderate-and high-dose DEHP groups(4.92±0.97,4.78±1.12g;0.93±0.09,0.85 ±0.08g)were lower than those of in the control group(6.05±1.36,1.12±0.12g).Conclusion DEHP can affect blastocy stim plantation in early pregnancy and embryo development in middle and late pregnancy.The results indicate that DEHP in moderate-and high-dose may result in early pregnancyloss and adverse fetal development.