Medical thermal imaging is a service for physicians available on request. One can only find significant changes of the skin temperature distribution in case of suspect of a disease. It is totally unacceptable to use a thermal imager for screening of diffuse and poorly defined complaints. An external blackbody reference source is highly recommended to control for measurement performance of the thermal imager, although temperature-measuring device might not be always available. The room temperature must be displayed in the examination room. When the target temperature is reached, its variation must be recorded over the time of the performed imaging session. Explain the person to be imaged the reason why thermal imaging is performed and the procedures necessary for recording valid and reliable thermal images. Different clinical questions require different body positions of the patient during acclimation and the body parts being imaged also differ in various indications for thermal imaging.