Regardless of stringent safety regulations and increased compound selectivity by pharmaceutical companies, prediction of toxicity in humans is still far from perfect and adverse drug reactions are still detected after drug marketing. High costs of failures due to toxicity has led pharmaceutical companies to search for screening methods that would allow detection of toxicity issues at an early stage and improve their preclinical and clinical toxicology. Thanks to the last decade's biotechnology revolution, new technologies like toxicogenomics have demonstrated the capacity to improve toxicity assessment. However, our understanding of toxicological mechanisms is still incomplete and a wide range of approaches must be used to gain insight into toxicity issues. Consequently, an array of in silico, in vitro and in vivo methods is utilized to predict toxicity and its causative mechanisms, improving drug development processes and minimizing costs of failure.