Context: Existential guilt is an important concept in cancer patients. However, the literature shows that the components of this concept are not well defined and specified. Hence, this study aimed at enhancing understanding of the characteristics of existential guilt and its differentiation from other similar concepts in the field of cancer. Evidence Acquisition: Focusing on cancer patients, Walker & Avant's approach was followed to clarify and analyze the concept of existential guilt. So, Web of Sciences (ISI), PubMed, ProQuest, Scopus, PsycINFO databases, and Google Scholar were searched, using 'existential guilt', 'guilt', and 'cancer' keywords to identify relevant studies with no time limitation. After screening and evaluation, 58 articles were identified, of which 26 were analyzed. Results: Initially, definitions, characteristics, antecedents, and consequences of the existential guilt concept were introduced. Then, a case model was explained to create a more clarified understanding of the concept and, eventually, some implications for the approach to cancer patients were proposed. Conclusions: The existence of different definitions and separate research pathways about the concept of existential guilt may indicate a sense of scatteredness. However, as shown in this study, one can come to a widely accepted understanding as well as a differential understanding of this concept; this clarification can, in turn, result in efficient and comprehensive psychological attention to cancer patients. Indeed, this concept analysis can pave the way for clinical interventions, operationalization, and research on this topic and population