This survey study explores the advance care planning choices among adults receiving maintenance dialysis who hold religious or spiritual beliefs., Key Points Question Is there an association between the self-reported importance of religious or spiritual beliefs and serious illness preferences among people who receive dialysis? Findings In this cross-sectional survey study of 937 patients receiving dialysis, most participants indicated that their religious or spiritual beliefs were behind their whole approach to life. Those for whom these beliefs were more important were more likely to favor resuscitation and a shared (vs patient-centered) decision-making role and less likely to have ever thought or spoken about stopping dialysis. Meaning These findings highlight the importance of religious or spiritual beliefs and the potential value of an integrative approach that includes spiritual care for people who receive dialysis., Importance Although people receiving maintenance dialysis have limited life expectancy and a high burden of comorbidity, relatively few studies have examined spirituality and religious beliefs among members of this population. Objective To examine whether there is an association between the importance of religious or spiritual beliefs and care preferences and palliative care needs in people who receive dialysis. Design, Setting, and Participants A cross-sectional survey study was conducted among adults who were undergoing maintenance dialysis at 31 facilities in Seattle, Washington, and Nashville, Tennessee, between April 22, 2015, and October 2, 2018. The survey included a series of questions assessing patients’ knowledge, preferences, values, and expectations related to end-of-life care. Data were analyzed from February 12, 2020, to April 21, 2021. Exposures The importance of religious or spiritual beliefs was ascertained by asking participants to respond to this statement: “My religious or spiritual beliefs are what really lie behind my whole approach to life.” Response options were definitely true, tends to be true, tends not to be true, or definitely not true. Main Outcomes and Measurements Outcome measures were based on self-reported engagement in advance care planning, resuscitation preferences, values regarding life prolongation, preferred place of death, decision-making preference, thoughts or discussion about hospice or stopping dialysis, prognostic expectations, and palliative care needs. Results A total of 937 participants were included in the cohort, of whom the mean (SD) age was 62.8 (13.8) years and 524 (55.9%) were men. Overall, 435 (46.4%) participants rated the statement about religious or spiritual beliefs as definitely true, 230 (24.6%) rated it as tends to be true, 137 (14.6%) rated it as tends not to be true, and 135 (14.4%) rated it as definitely not true. Participants for whom these beliefs were more important were more likely to prefer cardiopulmonary resuscitation (estimated probability for definitely true: 69.8% [95% CI, 66.5%-73.2%]; tends to be true: 60.8% [95% CI, 53.4%-68.3%]; tends not to be true: 61.6% [95% CI, 53.6%-69.6%]; and definitely not true: 60.6% [95% CI, 52.5%-68.6%]; P for trend = .003) and mechanical ventilation (estimated probability for definitely true: 42.6% [95% CI, 38.1%-47.0%]; tends to be true: 33.5% [95% CI, 25.9%-41.2%]; tends not to be true: 35.1% [95% CI, 27.2%-42.9%]; and definitely not true: 27.9% [95% CI, 19.6%-36.1%]; P for trend = .002) and to prefer a shared role in decision-making (estimated probability for definitely true: 41.6% [95% CI, 37.7%-45.5%]; tends to be true: 35.4% [95% CI, 29.0%-41.8%]; tends not to be true: 36.0% [95% CI, 26.7%-45.2%]; and definitely not true: 23.8% [95% CI, 17.3%-30.3%]; P for trend = .001) and were less likely to have thought or spoken about stopping dialysis. These participants were no less likely to have engaged in advance care planning, to value relief of pain and discomfort, to prefer to die at home, to have ever thought or spoken about hospice, and to have unmet palliative care needs and had similar prognostic expectations. Conclusions and Relevance The finding that religious or spiritual beliefs were important to most study participants suggests the value of an integrative approach that addresses these beliefs in caring for people who receive dialysis.