Background. Oxidative stress in schizophrenia may be caused partially by the treatment of patients with antipsychotics. The aim of the study was to establish the effects of polyphenol compounds derived from berries of Aronia melanocarpa (Aronox) on the plasma lipid peroxidation induced by ziprasidone in vitro. Methods. Lipid peroxidation was measured by the level of thiobarbituric acid reactive species (TBARS). The samples of plasma from healthy subjects were incubated with ziprasidone (40 ng/ml; 139 ng/ml; and 250 ng/ml) alone and with Aronox (5 ug/ml; 50 ug/ml). Results. We observed a statistically significant increase of TBARS level after incubation of plasma with ziprasidone (40 ng/ml; 139 ng/ml; and 250 ng/ml) (after 24 h incubation: P = 7.0 × 10(-4), P = 1.6 × 10(-3), and P = 2.7 × 10(-3), resp.) and Aronox lipid peroxidation caused by ziprasidone was significantly reduced. After 24-hour incubation of plasma with ziprasidone (40 ng/ml; 139 ng/ml; and 250 ng/ml) in the presence of 50 ug/ml Aronox, the level of TBARS was significantly decreased: P = 6.5 × 10(-8), P = 7.0 × 10(-6), and P = 3.0 × 10(-5), respectively. Conclusion. Aronox causes a distinct reduction of lipid peroxidation induced by ziprasidone.