Regular physical activity undoubtedly has many health benefits for all age groups. In the past decade, researchers and clinicians have begun to focus their attention on whether physical activity also can improve health outcomes of older adults who experience mild cognitive impairment (MCI) or dementia. This ongoing question is gaining relevance in light of the aging of the world population and with it the rise of age-related conditions, such as cognitive impairment. Not surprisingly, physical activity is among the potential protective lifestyle factors mentioned when strategies to delay or prevent dementia are discussed. The first large-scale multidomain intervention trials are under way to put this to the test. This review aims to give an overview of recent trials of physical activity in patients with MCI or dementia.