Background and Objectives: The complex concept of rational suicide, defined as a well-thought-out decision to die by an individual who is mentally competent, is even more controversial in the case of older adults. Materials and Methods: With the aim of better understanding the concept of rational suicide in older adults, we performed a systematic review of the literature, searching PubMed and Scopus databases and eventually including 23 published studies. Results: The main related topics emerging from the papers were: depression, self-determination, mental competence; physicians’ and population’s perspectives; approach to rational suicide; ageism; slippery slope. Conclusions: Despite contrasting positions and inconsistencies of the studies, the need to carefully investigate and address the expression of suicidal thoughts in older adults, as well as behaviours suggesting “silent” suicidal attitudes, clearly emerges, even in those situations where there is no diagnosable mental disorder. While premature conclusions about the “rationality” of patients’ decision to die should be avoided, the possibility of rational suicide cannot be precluded.