Introduction Neuropsychiatric symptoms (NPSs) in elderly patients with dementia are frequent in long-term care facilities (LTCFs) and are associated with adverse events. Telemedicine is an emerging way to provide consultation and care to dependent LTCF residents who may not have easy access to specialty services. Several studies have evaluated telemedicine for dementia care but to date, no study has evaluated its impact in the management of NPS in patients with dementia living in LTCF. Methods and analysis The Dementia in long-term care facilities: Telemedicine for the management of neuropsychiatric symptoms (DETECT) study is a 24-month multicentre prospective cluster randomised controlled study with two arms: a control arm (usual care) and an intervention arm (telemedicine consultation) for NPSs management. DETECT enrolled 20 LTCFs. The primary outcome is based on the acceptability of the telemedicine among the LTCF staff which will be assessed in the intervention group by quantitative and qualitative indicators. The rate of unscheduled hospitalisations and/or consultations due to disruptive NPSs, psychotropic drug use and health costs will be described in both groups. Approximately, 200 patients are expected to be recruited. Ethics and dissemination The study protocol was approved and sponsored by the French Ministry of Health. The study received ethical approval from the Toulouse University Hospital Institutional Review Board. We will communicate the final results to the public via conferences and results will also be submitted for publication in international peer-reviewed scientific journals.