Abstract This thesis examines and discusses a sample of the medieval hypocausts (stone-heating ovens) in the Baltic area. The medieval construction is thoroughly explained as well as the antique hypocaust in order to establish a base for the following discussion. The medieval hypocaust has been almost forgotten for a long period of time. The last time someone dealt with this category of finds were in the 1960’s by Swedish archaeologist Iwar Andersson and in the 1970’s by Danish archaeologist Johannes Hertz. Not one archaeologist, since the early 20th century, has tried to interpret these constructions in their social contexts. The focus has always been on the construction and the technique in itself, which doesn’t lead the research any further than to a functional interpretation.   The author applies a comparative method to the literary material that is used for the thesis and discusses the origins of the medieval technique, which types there are, what contexts they appear in, what buildings and activities they can be related to, if they represent status or necessity or both and who could afford to construct them in relation to the resources that was demanded and finally why the technique was abandoned.   Keywords: Medieval hypocaust, stone-heating oven, medieval, ancient technology, the Baltic area.