Aim: This literature review aims to describe, analyze and compare approaches to the phenomenon of missed/rationed/unfinished nursing care, in order to better our understanding of it. Design: A narrative literature review. Methods: A method of content analysis of studies published in the scientific databases PubMed, ScienceDirect, ProQuest, and Wiley Library Online was used. Studies were selected using a set of criteria and keywords for the period 2000–2018. Twenty-one studies were analyzed in the processing of the literature review. Results: We identified the four most common approaches or conceptual frameworks used to describe the phenomenon from the available literature – Missed Care, Implicit Rationing of Nursing Care, Task Undone and the theoretical proposition, Failure to Maintain, each of which explicitly describes a particular aspect of the phenomenon, and provides us with a theoretical framework and structure. Conclusion: This review contributes to the overview of particular approaches or theoretical frameworks used to understand the phenomenon. It is necessary to understand the terminology, and to use it appropriately. All approaches identified associations between the phenomenon and negative outcomes for patients as a quality-of-care indicator. Keywords: approach, conceptual framework, missed care, rationing care, unfinished care, failure to maintain.