Lies and deception are often used in the care for demented elderly and often with the best intentions. However, there is a strong moral presumption against all forms of lying and deceiving. The goal of this article is to examine and evaluate concrete examples of deception and lies in dementia care, while addressing some fundamental issues in the process.It is argued that because dementia slowly diminishes the capacities one needs to distinguish between truths and falsehoods, the ability to be lied (...) to also disappears. When the moral reasons to reject lying are explored, it becomes clear that most of them also hold where demented patients are concerned, though this also depends on the capacities of the patient. Lying, though prima facie wrong, can sometimes be justified with an appeal to well-being. The relationship between well-being and the truth is further explored. Two examples of deceiving demented patients for reasons of beneficence are discussed, from which it can be concluded that although in some cases beneficent lies or deception will not enhance patients’ well-being, there are circumstances in which they do. In general, methods that enhance the well-being of the patient without deception or lies should be favored above options that use deceit, and methods of getting the truth across without hurting the patient should be favored above blunt honesty. Finally, it is important to note that not only the patient but also the nursing and medical staff can be affected by the use of lies and deception. (shrink)