Phthalates are known to affect the development of regions within the hippocampus, however the mechanisms of these toxic effects are not well known. Stress is also known to have detrimental effects on the hippocampus. This study aimed to determine whether phthalates affect hippocampal development, and whether there is an associated activation of HPA axis. DEHP was injected in juvenile rats daily from PND 16 – PND 22. Brain tissue samples were analyzed by immunohistochemistry to quantify developing neurons. The Golgi – Cox Impregnation method was used for detailed morphological analyses. Blood samples were analyzed for corticosterone levels. The CA3 of males showed a decrease in the size of the area of basal dendrites at the middle and highest dose of DEHP treatment, while the DG of females showed a decrease in number of spines at the highest dose, and a decrease in the dendrite length at only the lowest dose.