4-Chlorophenoxy acetic acid (4-CPA) is one of the plant growth regulators that are widely used in greenhouses to increase yield and the quality of products. Plant growth regulators do not produce significant effects on organisms; however, their remnants on plants due to either high dose or inappropriate use may lead to certain adverse effects on humans. High doses of 4-CPA have been reported to cause hepatocellular necrosis. In our study, we investigated the oxidant and anti-oxidant parameters in the liver tissues of male and female rats exposed to 4-CPA before sexual maturity. The study was implemented on 20 day-old, 80 Wistar albino rats. Forty rats received 4-CPA/day until 50 days of age. The rats were randomized into five groups (a control group, a saline group and three 4-CPA groups that received 25 to 50 to 100 mg/kg/day, respectively); and each group were further divided according to gender, making a total of 10 groups. Comparison of each gender in control and saline groups showed no difference for MDA, GSH and NOx levels. However, exposure to 4-CPA caused a dose-dependent increase in MDA and a decrease in NOx levels. These findings may be the result of 4-CPA's effects on lipid peroxidation and inflammatory reactions in liver tissue.