BACKGROUND: Hearing and vision impairments are highly prevalent in people with dementia and may have a negative impact on quality of life and other dementia-related outcomes. Intervening to optimise sensory impairment and support sensory function may be a means of improving dementia-related outcomes. The SENSE-Cog trial will test whether a home-based multi-part sensory intervention is effective in improving quality of life and other key outcomes in people with dementia and hearing or vision problems (or both) and their companions. METHODS: This is an European, multi-centre, observer-blind, pragmatic, randomised controlled trial. Three hundred fifty four people with dementia and hearing or vision impairment (or both) and their companions will be randomly assigned to receive either "care as usual" or a multi-component sensory intervention including assessment and correction of hearing or vision impairments (or both), home-based (maximum 10 visits over 18 weeks), therapist-delivered sensory support (that is, adherence to devices; improving the sensory environment (that is, lighting), communication training, and sign-posting to other support agencies). Change from baseline to intervention end (18 weeks) and post-intervention (36 weeks) will be compared between the two arms in the following outcomes: quality of life (primary endpoint), sensory and cognitive functional ability, relationships, mental well-being, health resource utilisation and cost-effectiveness. DISCUSSION: This is one of two articles outlining the SENSE-Cog trial. Here, we describe the protocol for the effectiveness of the SENSE-Cog intervention. A parallel and complementary process evaluation will be described elsewhere. If the SENSE-Cog trial demonstrates that the sensory intervention improves outcomes in dementia, we will make a toolkit of training materials, resources and information available to health and social care providers to implement the intervention in routine practice. This will be a significant contribution to the therapeutic management of people with dementia and sensory impairment. TRIAL REGISTRATION: ISRCTN (Trial ID: ISRCTN17056211 ) on 19 February 2018.< Réduire