Debt in kind in the İslamic Law

According to the classification which finds it's basis in Roman law, an obligation has three basic elements; debtor, creditor and prestation. In that ancient judicial system, three diffferent types of "the prestation" which consists the subject of the obligation had been located as "acting", "avoiding from an act" and "giving". Among these types, "giving" can appear in three different types as kind (genus), piece (species) and money debts. In classical literature of fiqh, while the concept "dayn" comprises kind and Money debts, the concept "ayn" corresponds the debts in piece. The rules that relates to the obligations differantiates from each other according to the type of the prestation. In this thesis it was aimed to present an example between the differences of the rules that relates to the obligation, which differentiates due to the kind of prestation, by examining the debts in kind in comparison with the debst in piece in accordance with the approaches of the four main schools of the fiqh. In this respect, after we outlined the nature of the concepts "ayn" and "dayn" in general, we elaborated the issues like the determination of the subject of the obligation, the requirements relates to the subject of the obligation, the using the subject of the debt before obtaining, the securing the debt and the fullfillment of the debt. Keywords: Prestation, debt in kind (genus), debt in piece (species), ayn,dayn.