Background: Recently, euthanasia and assisted suicide (EAS) in patients with psychiatric disorders, dementia, or an accumulation of health problems has taken a prominent place in the public debate. However, limited is known about this practice. The purpose of this study was threefold: to estimate the frequency of requesting and receiving EAS among people with (also) a psychiatric disorder, dementia, or an accumulation of health problems; to explore reasons for physicians to grant or refuse a request; and to describe differences in characteristics, including the presence of psychiatric disorders, dementia, and accumulation of health problems, between patients who did and did not request EAS and between patients whose request was or was not granted. Methods: A nationwide cross-sectional survey study was performed. A stratified sample of death certificates of patients who died between 1 August and 1 December 2015 was drawn from the central death registry of Statistics Netherlands. Questionnaires were sent to the certifying physician (n = 9351, response 78%). Only deceased patients aged ≥ 17 years and who died a non-sudden death were included in the analyses (n = 5361). Results: The frequency of euthanasia requests among deceased people who died non-suddenly and with (also) a psychiatric disorder (11.4%), dementia (2.1%), or an accumulation of health problems (8.0%) varied. Factors positively associated with requesting euthanasia were age (< 80 years), ethnicity (Dutch/Western), cause of death (cancer), attending physician (general practitioner), and involvement of a pain specialist or psychiatrist. Cause of death (neurological disorders, another cause) and attending physician (general practitioner) were also positively associated with receiving euthanasia. Psychiatric disorders, dementia, and/or an accumulation of health problems were negatively associated with both requesting and receiving euthanasia. Conclusions: EAS in deceased patients with psychiatric disorders, dementia, and/or an accumulation of health problems is relatively rare. Partly, this can be explained by the belief that the due care criteria cannot be met. Another explanation is that patients with these conditions are less likely to request EAS.