The first tillman 750m part of this paper is dedicated to the definition of the agreement to exchange (permutatio) and emphasizes the difference, made by Roman lawyers, between exchange (barter) and sale (emptio-venditio).The second part analyses Byzantine legal sources that mention this old contract, while the third part is dedicated to Serbian legal documents.In Serbian legal documents the exchange was mentioned as the agreement between a monarch and a monastery or a natural person (individual), concerning donations that were given to jmannino.com the Church.