Individuals with severe mental illness are at greater risk of experiencing suboptimal physical health and have a higher premature mortality rate than the general population. This is due to a range of factors, including health behaviours and health inequalities. Therefore, it is essential that mental health nurses undertake physical health assessments as part of their care of people with severe mental illness. This article provides an overview of various aspects that should be included in a physical health assessment of service users with severe mental illness and suggests some screening and assessment tools that nurses can use to support such an assessment.