Synthetic plant regulators are used extensively and uncontrollably in order to increase agricultural production. The 4-chlorophenoxyacetic acid used for this purpose is contaminating soil and water, and leaving residue on the products. Therefore, it cannot be ruled out that there may be adverse effects on nontarget organisms and especially on animal health. In this study, the effects of oxidative stress and antioxidant enzymes were investigated in the primary hepatocyte culture of Lake Van fish (Alburnus tarichi, Guldenstadt 1814) exposed to 4-chlorophenoxyacetic acid. Statistically significant reductions in superoxide dismutase, catalase, glutathione peroxidase, and glutathione-S-transferase enzyme activities and reduced glutathione levels were observed in comparison with the obtained findings in the control group (P <= 0.05). There was also a significant increase in the level of malondialdehyde, a product of lipid peroxidation (P <= 0.05). As a result, it was determined that Lake Van fish treated with different concentrations of 4-chlorophenoxyacetic acid exhibited oxidative stress and lipid peroxidation in the primary hepatocyte cell culture.