Although the vital role of informal carers has been acknowledged in government policy documents in the UK, the information needs of informal carers are not well documented. There is also uncertainty about where carers get their information from and whether they are satisfied with the information they receive. This study aimed to examine the information needs and sources of information for informal carers in the acute cancer setting; the informal carers of a sample of women treated for breast cancer. Both quantitative and qualitative data were collected from semi-structured interviews with 50 informal carers. Measures of information needs and sources were administered in addition to an in-depth exploration of information needs. The priority information needs of carers related to cure, spread of disease and treatments, a similar profile to that found for women with breast cancer in previous work. The main source of information for carers was the person they were caring for, although written information was also valued. Health professionals need to ensure that patients are well informed so that patients can provide information for carers and also need to take advantage of any opportunities to directly assess the information needs of carers to enable them to be more effective in their caring role.