Louis Pasteur: a controversial figure in a debate on scientific ethics.

Louis Pasteur long has been heralded as the "father of modern hygiene, public health and much of modern medicine," despite early controversies regarding his findings and methodology. A recently published biography, however, has shed new light on both Pasteur's scientific acumen and integrity. Reactions to this portrayal have been mixed. This article provides an overview of Pasteur's life and the debate regarding his scientific discoveries and honesty that has ensued for more than 100 years, with insights gained from both supporters and critics of the new biography by Gerald L. Geison.