The purpose of this literature review was to identify research and current literature surrounding nursing students' understandings of mental health. The aim is to share findings from an extensive international and national literature review exploring undergraduate nurse education specific to mental health content. Data were collected utilising a comprehensive search of electronic databases including CINAHL (EBSCO), MEDLINE, and PsycINFO 1987-(Ovid) from 2008 to 2016. The initial search terms were altered to include undergraduate, mental health, nursing, education, experience, and knowledge. Three content themes emerged which included: 1. Undergraduate nursing students' knowledge has been considered compromised due to concerns relating to the variation and inconsistencies within the comprehensive nursing curriculums representation of mental health, 2. Undergraduate nursing students knowledge of mental health is thought to be compromised due to the quality of mental health theoretical and experiential learning opportunities, and 3. Research indicates that nursing students' knowledge of mental health was influenced by their experience of undertaking mental health content. Based on these findings greater consideration of students' understandings of mental health is required.