The author analyses condictional claims (claims associated with condictio) in Roman law, in which turpitudo, or immorality, was involved in certain way. Firstly he analyses these claims in three different Roman procedural systems, legis actio per condictionem, condictio of the formulary procedure and different condictiones of the postclassical and Justinianic law and cognitio extraordinaria. Afterwards, the meaning of turpitudo and turpis in Roman law is discussed. In the central part of the text the author deals specifically with the typology of the instances of ob turpem rem condicere in the sources, in other words he analyses condictio ob turpem (vel iniustam) causam from the Justinian's codification. Analysing the extant literature on the matter, finally he gives a reinterpretation... regarding main functions of the ob turpem rem condicere in Roman law, while suggesting a possible explanation of its origins and its consequent relevance in the general Roman condictional system.