Poor diet, smoking, a lack of physical activity and excessive alcohol intake are just some of the factors that can contribute to a range of debilitating long-term conditions. Lifestyle risk factors can have a disproportionate impact on more vulnerable groups within society, such as people with mental health problems. In the first in a two-part series on mental health and long-term conditions, this article looks at the prevalence of physical illness among this service user group and how this affects mortality and morbidity. It also examines factors influencing physical health, and discusses the role nurses can play in screening for physical conditions in vulnerable groups.