Mitochondria are critical organelle and perform 90% energy production and control cell survival (apoptosis) in the cells. Drug-induced mitochondrial dysfunction is a key factor in the onset of drug-induced liver injury. Therefore, monitoring compounds for mitochondrial toxicity is a crucial element of drug toxicity screening program and toxicology studies. Culturing cells in glucose-deprived galactose media increases the reliance of the cells on mitochondrial oxidative phosphorylation (OXPHOS) to obtain ATP instead of glycolysis. By comparing the toxic effects of different drugs in the glucose and galactose media, mitochondrial impairment is detected. BioIntersect provides a simple and robust assay for measuring mitochondrial toxicity in live cells using plate reader.