The aim of this study is to investigate the effect of low-level laser irradiation on oxidative stress parameters in hepatic mitochondrial fractions of rats under the conditions of BPA administration. Short-term BPA-exposure results in the induction of free radical processes in hepatic mitochondria by the enhanced generation of O2• –and decreased activity of antioxidant enzymes. At the same time, low level laser irradiation reduces the prooxidant effect of this xenobiotic in mitochondria by the enhancement of the antioxidant activity, which is primarily associated with conformational changes induced by a short-term increase in the temperature of light-absorbing biomolecules. This effect was observed only in the case of LLLI after BPA exposure.