Social networks have been shown to be smaller in individuals with severe mental illness than in the general population. Patients' social networks and social support may impact on their utilisation of psychiatric services. This literature review focuses on social networks, social support and mental health service use in patients with mental illness. Most studies suggest that smaller social networks or less social support are associated with more frequent hospitalisation. Qualitative aspects of the social network are also related to the risk of hospitalisation. The relationship between social networks and other types of service use is not established.