MDMA [(+/-)3,4-methylenedioxymethamphetamine, also known as ecstasy] is a popular recreational drug among women of reproductive age. The objective of this study was to investigate the long-term neurobehavioral consequences of early developmental MDMA exposure. On postnatal days (PD) 1-4, Sprague-Dawley rats received two 10 mg/kg injections of MDMA with an inter-dose interval of 4 h. Male subjects were tested in adulthood for their performance in an object-recognition memory task and for their thermal and behavioral responses to an acute MDMA challenge (10 mg/kg i.p.). Neonatal MDMA administration did not alter working memory in the object-recognition test in young adulthood (PD 68-73) and there were no differences in radiolabeled citalopram binding to the serotonin transporter at this age. However, the pretreated animals showed increased thermal dysregulation and serotonin syndrome responses (particularly headweaving stereotypy) following the MDMA challenge. These results add to the growing literature demonstrating that developmental MDMA administration can lead to long-lasting functional abnormalities, and they further suggest that the offspring of ecstasy-using women may be at risk for enhanced sensitivity to this drug due to their earlier exposure.