The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) has been widely used in agriculture and forestry since the 1940s. 2,4-D has been shown to produce a wide range of adverse effects—from embryotoxicity and teratogenicity to neurotoxicity—on animal and human health. The purpose of this study was to determine the possible effects of pre- and postnatal exposure to 2,4-D on oxidative stress in ventral prostate, ovary and breast. Pregnant rats were daily exposed to oral doses of 70 mg/kg/day of 2,4-D from 16 days of gestation up to 23 days after delivery. Then, the pups were sacrificed by decapitation at postnatal day (PND) 45, 60, or 90. Antioxidant enzyme activities and some parameters of the oxidative stress were assessed in ventral prostate, breast, and ovary. Results show that 2,4-D produced three different effects. First, it increased the concentration of some radical oxygen species and the rates of lipid peroxidation and protein oxidation in ventral prostate, thereby causing oxidative stress at all ages studied. Although an increase in the activity of some antioxidant enzymes was detected, this seemed to have been not enough to counteract the oxidative stress. Second, 2,4-D promoted the oxidative stress in the breasts, mainly during puberty and adulthood, probably because the developing gland is more sensitive to xenobiotics than the adult organ. Third, 2,4-D altered the activity of some antioxidant enzymes and increased lipid peroxide concentration in the ovary. This effect could reflect the variety of ovarian cell types and their different responses to endocrine changes during development. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2013.