Phthalates are synthetic chemicals added to plastics to increase their flexibility, however they easily migrate out of the plastic into the environment. Previous research has shown that early life exposure to DEHP results in altered neurodevelopment. DEHP was administered once daily from P18-23. Wildtype C57Bl/6 and transgenic AldHl1- L10:GFP mice were used to assess behaviour and astrocytic changes in the PFC, respectively. Behavioural and histological measurements were assessed at P29 and P49 in males and females. Our results suggest that male mice exposed to DEHP exhibit acute hyperactivity and decreased anxiety. These effects were not seen at P49, and no differences were seen at either time point in females. No changes in astrocyte number or astrocyte activation were observed. In conclusion, early-life DEHP exposure appears to have acute anxiolytic effects only in males, and these effects do not seem to be mediated through astrocytic changes in the PFC.