General medical practitioners (GPs) and members of the primary care team have a pivotal role in supporting unpaid carers in their caring role and helping them to maintain their own health and well-being. This paper investigates the difference that caregiving makes to individuals’ access to and use of GP and primary care services. It is based on longitudinal analysis of carers’ contacts with GPs, and a review of the literature including evaluations of measures to improve primary-care-based support for carers. Men increase their consultation rates with GPs when taking on a caring role. In contrast, women who look after someone in the same household and carry heavy caring responsibilities have relatively less contact with GPs than expected. According to the literature, carers report a range of difficulties accessing primary health care. A five-fold typology is described covering barriers arising from: professional responses to the carers’ role; the way services are organized and delivered; language or culturally held beliefs and practices; carer or care recipient characteristics; and unmet information needs. Various measures to improve carers’ access to primary care have been introduced to overcome these barriers, but robust evidence of cost and utility is required to judge their acceptability and effectiveness for both carers and GPs. Although good practice guides, quality standards and evaluation tools are available to help improve primary care support for carers, further investigation of carers’ help-seeking for health care, and the factors involved, is required to underpin the prospects for developing a genuine partnership between unpaid carers and health professionals.