**Background:** Population aging and medicalization of older age have increased the importance of advance care planning, yet individuals are asked to make choices about end-of-life situations they may have little knowledge about. Perceptions and knowledge regarding end-of-life health care influence advance care planning, but little is known about the accuracy of these perceptions among older adults in the general population. This study aimed to assess older adults' perceptions of medical end-of-life situations in Switzerland, their accuracy, and associations with sociodemographic characteristics.
**Methods:** Data were drawn from wave 8 (2019/2020) of the Swiss part of the Survey of Health, Ageing, and Retirement in Europe (SHARE), a population-based cohort study. The analytical sample included 1217 respondents aged 58 years and older (cooperation rate: 94.3%). Participants completed a paper-and-pencil questionnaire assessing the subjective likelihood of 11 end-of-life situations on a 4-point scale: very unlikely (0-25%), rather unlikely (26-50%), rather likely (51-75%), and very likely (76-100%). Situations covered cognitive impairment (dementia at ages 75 and 95), medical decision-making, pain management, artificial nutrition and hydration, cardiopulmonary resuscitation, hospital admission for pneumonia in advanced dementia, fourth-line chemotherapy, and place of death (nursing home, hospital, home). Accuracy was determined by comparing responses to published epidemiological data. Statistical analyses included weighted proportion estimations, interval regressions for partial associations, and probit regressions for accuracy, with standard errors clustered at the household level.
**Key Results:** The sample was 48% female, median age 65 years, with 22% aged 75+ years. Most respondents had a partner (74%), secondary education (66%), and reported making ends meet easily (58%). Perceptions were heterogeneous and often inaccurate. Respondents overestimated dementia prevalence at both ages 75 and 95. They overestimated the success of cardiopulmonary resuscitation for a 70-year-old (actual survival <8%), the utility of fourth-line chemotherapy (actual benefit ~13.6%), hospital admission for pneumonia in advanced dementia, and artificial nutrition and hydration in the dying phase, while underestimating the effectiveness of pain management. Less than 28% of respondents correctly assessed the likelihood of dying in a nursing home, hospital, or at home, respectively. In probit regression analyses of accuracy scores (range 0-11), women were more likely to select correct answers than men (p<0.01). Respondents aged 75+ years had more accurate perceptions than those aged 58-64 (p<0.01). Respondents from the German-speaking region were more accurate than those from the French-speaking region (p<0.01). Respondents reporting difficulty making ends meet were less likely to choose correct answers compared to those with financial ease (p<0.05).
**Clinical Implications:** The wide variation and low accuracy of end-of-life perceptions among older adults in Switzerland suggest considerable scope for communication interventions about the reality of end-of-life health and health care. Misperceptions—particularly overoptimistic views of CPR survival, chemotherapy efficacy, and artificial nutrition benefits, alongside underestimation of pain management effectiveness—may lead to unrealistic expectations, disappointment for patients and families, and compromise the quality and reliability of advance care planning. Targeted educational efforts may be especially needed for men, individuals with financial difficulties, and those from French-speaking regions, who demonstrated less accurate perceptions. Improving knowledge about end-of-life realities could enable older adults to prepare and manage their end of life more effectively.