Hyperthermia is a heat-treatment. It is widely used in various medical fields and has a well-recognized effect in oncology. Its effect is achieved by overheating of the targeted tissues. It is an ancient treatment and a promising physical approach with lack of acceptance by the serious medical use. To accept the method we need strong proofs and stable, reproducible treatment quality, but we are limited by biological, physical/technical and physiological problems. However, the main point--I believe--is the incorrect characterization and unrealistic expectations from this capable method. The temperature concept of the quality assurance guidelines has to be replaced by the heat-dose sensitive characterization, pointing the essence of the hyperthermia method.