Background: Mental health issues reported among college-aged individuals have increased. Prevalence of these issues has an established impact on students' personal, professional, and academic outcomes. Graduate students experience unique stressors that impact their mental health. In particular, engineering graduate students have lower help-seeking tendencies, which can impact the severity and length of their mental health problems. Purpose: We investigate the literature concerning engineering graduate students' mental health, focusing on academic outcomes, mental health measures, and mental health findings, to highlight gaps in current literature and the need for further research. Scope/Method: Five research databases, EBSCO: CINAHL, EBSCO: PsycINFO, ProQuest: ERIC, PubMed, and Scopus, were searched in a scoping literature review. Inclusion and exclusion criteria were applied during the screening process. Peer-reviewed publications (i.e., articles and conference papers) were identified and coded for study focus, keywords, participants and institution(s), journal discipline, study type, methods used, and work referenced, in addition to academic outcomes, mental health measures, and mental health findings. Results: Nineteen of the 4,826 unique studies identified were included in the review. Ten academic outcomes and 13 mental health measures were discussed. Mental health findings were grouped into five themes: social support and sense of belonging; student-advisor relationship; cultural barriers faced by international students; gender and racial stereotypes; and generalized findings. Conclusions: Research on engineering graduate students' mental health is limited. Given that mental health has direct ties to students' well-being and ultimately their success, engineering education researchers should focus on studying students' experiences, sharing these findings, and communicating best practices for all stakeholders.