Background: Several countries have regulated euthanasia and physician-assisted suicide (PAS). Research has looked at the experiences of patients, family, and professionals. However, little is known of the effects on bereaved individuals. Aims: We aimed to assess (a) what is known about the grief and mental health of people bereaved by euthanasia or PAS and (b) the quality of the research. Method: Systematic review according to PRISMA guidelines with searches in Cinahl, Embase, PsycINFO, Pubmed, and Scopus. Results: The searches identified 10 articles (eight studies), and the study quality was fair. People bereaved by euthanasia/PAS generally had similar or lower scores on measures of disordered grief, mental health, and posttraumatic stress compared with those who died naturally. Lack of social support and secrecy may compound their grief. Being involved in the decision-making process and having the feeling of honoring the deceased’s will may facilitate their grief. Limitations: Studies used self-reports from non-random self-selected participants, were retrospective, and were conducted in only three countries. Conclusion: There is little evidence of increased risk of adverse grief or mental health outcomes in people bereaved by euthanasia/PAS. As more countries legalize assisted dying, high-quality studies of the factors that may hinder or facilitate the grief process are needed.