Informal carers provide important emotional support to patients having chemotherapy and assistance in monitoring and managing side-effects. If they are inadequately supported in this, patient and carer morbidity may result. This study explored needs of informal carers supporting patients with cancer having chemotherapy. The study used a mixed methods approach. Carers of colorectal or lymphoma cancer patients at one comprehensive cancer centre participated. Questionnaire data informed semi-structured interviews conducted with a subsample of respondents.