Fault (culpa) seems to be an interdisciplinary category, occurring among others in criminal and civil law, both material and procedural. Despite the undisputed presence of this concept in the science of criminal and civil law and the frequent use of it by the legislator, this term has not been defined in any law. The meaning of fault is not described in a uniform manner by the legal doctrine. Although the same concept is used in different scientific disciplines, it is not clear whether fault should be understood identically in each of them. This article is an attempt at fragmentary analysis of the issue of identity of the term “fault” in Polish law and focuses on discussing the similarities and differences in the approach to defining this concept in criminal law and on the basis of provisions on liability for tort.