Background: Particularly with ageing populations, dementia and stroke and their resultant disability are worldwide concerns. Much of the support for people with these conditions comes from unpaid carers or caregivers. The carers' role is often challenging and carers themselves may need support. General practice is often the first point of contact for people with these conditions and their carers, making it potentially an important source of support. This systematic review therefore synthesised the available evidence for the impact of supportive interventions for carers provided in general practice. Methods: PRISMA guidelines were adopted and the following databases were searched: MEDLINE; EMBASE; the Cochrane Library; PsycINFO; CINAHL Plus; Applied Social Sciences Index and Abstracts and Healthcare Management Information Consortium. Results: Two thousand four hundred eighty nine results were identified. Four studies, involving 447 carers, fitted the inclusion criteria. Three of these came from the United States of America. None investigated supportive interventions for carers of people with stroke. Primarily by the provision of information and educational materials, the interventions focussed on improving carer mental health, dementia knowledge, caregiving competence and reducing burden, difficulties and frustrations. Overall the evidence suggests that these interventions may improve carer well-being and emotional health but the impact on physical health and social variables was less clear. However, the diversity of the carer outcomes and the measures used means that the findings must be viewed with caution. Conclusions: Unpaid carers pay an essential role in caring for people with stroke and dementia and the dearth of literature investigating the impact of supportive interventions for these carers of is surprising. The available evidence suggests that it may be possible to offer support for these carers in general practice but future research should consider focussing on the same outcome measures in order to allow comparisons across interventions.