3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) use has risen among women of childbearing age. Consequently, there is a substantial risk for fetal exposure from women who are, or become pregnant while abusing MDMA. However, attempts to demonstrate that prenatal MDMA results in neurochemical alterations in rat models have failed. MDMA administration to neonatal rats (third trimester equivalent) results in significant and persistent neurochemical and behavioral alterations, yet human epidemiologic data suggest that the vast majority of prenatal exposure is limited to the first trimester. The following study was conducted to reexamine the potential for prenatal MDMA administration to produce lasting postnatal neurochemical and behavioral alterations using a new rodent model. Pregnant rats were administered twice-daily injections of MDMA (15 mg/kg sc) or saline from embryonic days (E) 14-20. Prenatally exposed pups were examined on postnatal days (P) 3 and 21. At P3, MDMA offspring showed reductions in the dopamine metabolite homovanillic acid which persisted through P21, along with reductions in the serotonin (5-HT) metabolite, 5-HIAA. Prenatally exposed MDMA animals at P21 also had reduced dopamine and 5-HT turnover in the nucleus accumbens. Increases in tyrosine hydroxylase fiber density were found in the frontal cortex, striatum and nucleus accumbens of MDMA animals. In addition, prenatal MDMA significantly increased locomotor activity of P21 pups in a 20-min novel cage environment. These findings provide the first evidence of lasting neurochemical and behavioral alterations following prenatal MDMA. Further investigation is warranted to elucidate possible mechanisms of action and to monitor children gestationally exposed to MDMA.