Ketoconazole was first considered as a more or less safe drug. When used on a very large scale, however, it became obvious that this drug, as others mainly metabolized in the liver, can cause liver damage, i.e. chemical hepatitis sometimes even leading to death. Such very rare events seem to be linked to the protracted use of ketoconazole. Taking into account what is now known on the rational use of ketoconazole it still is a drug with a favourable benefit risk ratio.