With the emerging focus on home-based care, there is an increasing demand on spouses to look after their chronically ill partners at home. The theoretical aspects of caring have been much discussed in the literature, but the pragmatic aspects have received less attention. Carer stress has been explored, but little has been written about the meaning of caring to informal carers. The aim of this paper is to report one of the major themes that emerged from a study conducted between 1998 and 1999 to explicate the meaning of caring from the perspective of spousal carers for people with multiple sclerosis in order to shed light on and understand the challenges and demands these carers encountered. An interpretive phenomenological approach was used to describe spousal carers' experiences of caring for their partner. Ten spousal carers of people with multiple sclerosis participated. Data were collected through unstructured in-depth interviews and analysed by the method of hermeneutic analysis. This paper presents one of the major themes identified: 'caring as worrying'. While the meaning of caring that emerged from this theme supports many of the philosophical understandings of caring as discussed in the literature, worrying as a care responsibility provides a further insight. Caring as worrying describes caring as a complex emotional relationship of responsibility in these participants. They worried about their partners, their relationships with their partners and their future. They also worried about their own health, institutional care, and lack of government support. Spousal carers' worries have significant implications for health care professionals. The findings provide insight into the concerns and worries the carers of people with multiple sclerosis face when caring for their chronically ill partners at home.