Background. There is a growing appreciation of the role and needs of carers for people with mental health problems. Carers are a diverse group, including partners, relatives and friends who are seen as such by service users. Methods. Sixty-four carers of people with severe mental health problems served by four different mental health care providers were interviewed using the Experiences of Care-giving Inventory. The districts were selected to differentiate services that are targeted at more severely impaired users from those that include a wider spectrum, and to contrast services that have greater integration between health and social care providers with those whose health and social care agencies operate relatively discretely. Results. In the two districts where service users had more severe mental health problems, carers worried more about negative symptoms and thought less about good aspects of the caring relationship. In the two districts where health and social services worked more closely together, carers worried significantly less about the need to back up services. Conclusions. These findings suggest that service organisation can affect carers, in particular that integration between health and social care for people with mental health problems may benefit carers in ways that were hitherto unproven. They highlight the needs of carers for younger people. They show that the ECI is a useful instrument in measuring the impact of caring for people with severe mental health problems.