Background: Although most cases of dementia are caused by Alzheimer's disease or vascular dementia, around 10-15% of cases are due to other disorders, including dementias with Parkinsonian features, Huntington's disease, frontotemporal dementia, human immunodeficiency virus (HIV), and alcohol. Aims: These less common dementias are important as they may have differing clinical features and require different approaches to diagnosis and management. This paper seeks to provide relevant information for nurses about symptoms, diagnosis and management of some of the less common dementias. Methods: This is one of two connected papers, and provides a clinical overview of Parkinsonian dementias and Huntington's disease. It provides a narrative, rather than systematic, review of the literature. Findings: Parkinsonian dementias comprise Parkinson's disease dementia, dementia with Lewy bodies and so-called Parkinson's-plus syndromes (multi-system atrophy, progressive supranuclear palsy, and corticobasal degeneration). Huntington's disease is an inherited neuropsychiatric condition. Each has a distinctive clinical picture, with combinations of cognitive, neuropsychiatric and neurological symptoms but approaches to treatment and care are essentially supportive. Conclusions: Nurses have an essential role in supporting people with dementia, as well their families and carers, throughout the course of dementia from diagnosis to end of life care. They are often best placed and have the necessary skills to create appropriate care plans and to provide care management.