Background: Dementia affects the mood of people with dementia but also of their caregivers. In the coming years, the number of people with dementia will increase worldwide and most of them will continue to live in the community as long as possible. Home-based psychosocial interventions reducing the depressive symptoms of both people with dementia and their caregivers in their own home are highly needed. Methods/Design. This manuscript describes the design of a Randomised Controlled Trial (RCT) of the effects of a home-based exercise and support programme for people with dementia and their caregivers. The aim is to randomly assign 156 dyads (caregiver and dementia diagnosed person) to an intervention group or a comparison group. The experimental group receives a home programme in which exercise and support for the people with dementia and their caregivers are combined and integrated. The comparison group receives a minimal intervention. Primary outcomes are physical health (people with dementia) and mood (people with dementia and caregivers). In addition, to get more insight in the working components of the intervention and the impact of the intervention on the relationship of the dyads a qualitative sub-study is carried out. Discussion. This study aims to contribute to an evidence-based treatment to reduce depressive symptoms among people with dementia and their caregivers independently living in the community. Trial Registration. The study has been registered at the Netherlands National Trial Register (NTR), which is connected to the International Clinical Trials Registry Platform of the WHO. Trial number: NTR1802. © 2011 Prick et al.; licensee BioMed Central Ltd.