The number of people suffering from dementia will rise considerably in the years to come. This will have important implications for society. People suffering from dementia have to rely on relatives and professional caregivers when their disorder progresses. Some people want to determine for themselves their moment of death, if they should become demented. They think that the decline in personality caused by severe dementia is shocking and unacceptable. In this context, some people consider euthanasia as a way to avoid total deterioration. In this article, we discuss some practical and ethical dilemmas regarding euthanasia in persons with severe dementia based on an advance euthanasia directive.