Diethylhexyl phthalate (DEHP) is an estrogen‐like compound widely used as a commercial plasticizer and present in medical devices, tubing, food containers and packaging. It is considered an endocrine disruptor and studies on experimental animals showed that exposure to DEHP can alter the function of several organs including liver, kidneys, lungs and reproductive system, particularly the developing testes of prenatal and neonatal males. Exposure to DEHP has been proposed as a potential human health hazard. This study assessed the effects of DEHP on folliculogenesis and oocyte maturation using the mouse as the experimental model. Newborn female mice were hypodermically injected with DEHP at doses of 20 and 40 μg/kg per body weight following different exposure regimens during the weaning period. We found that DEHP altered both folliculogenesis and oocyte development. In particular, DEHP exposure significantly decreased the number of the primordial follicles at pubertal and adult age by possibly accelerating the rate of follicle recruitment dynamics, reduced and/or delayed the level of imprinted gene methylation in the oocytes and increased metaphase II spindle abnormalities in oocytes matured in vitro. Furthermore, the weight of pups and litter size of mothers exposed to DEHP were significantly lower than controls. Finally, the number of primordial follicles appeared significantly reduced also in the F1 offspring at the adult age. These results show that DEHP may have a number of adverse effects on oogenesis, especially when exposure occurs during early postnatal age, arising concerns about the exposure of human female infants and children to this compound. Environ. Mol. Mutagen. 54:354–361, 2013. © 2013 Wiley Periodicals, Inc.