There is no doubt that animal testing has played a role in scientific and biomedical progress. However, without mentioning ethical issues, the animal ‘model’ does not fully meet the needs of scientific progress. It fails in terms of cost, speed and relevance to humans, says Thomas Hartung, director of the Center for Alternatives to Animal Testing. Today, we have a wide range of evidence showing that it is no longer justifiable to continue using animals in certain scientific fields.