There is a growing recognition that the carers of cancer patients require information. A key source of this information is the formal health care system that patients, and thus carers, encounter. However, the research literature suggests a lack of clarity on the part of service providers concerning the type, amount, timing and purpose of information for carers. This lack of clarity is reflected in the ways carers have been ‘tacked on’ to patients and thus are often treated as co-clients. That carers are also an active participants in the illness scenario is not always fully recognized, resulting in failure to provide appropriate information. Carers’ interactions with health service providers are complex and context bound, and entail potential tensions of allegiance in the arena of information exchange. This article suggests that the following research and practice is required: a clearer understanding of the informational needs of carers in variable situations, specific ways to address these needs, where carers ‘fit in’ to the health care system, and how processes of information exchange with carers can be improved.