Background. The proportion of older adults (OAs) is increasing throughout the developed world. Social isolation is a recognised problem for this sector. Technology is regarded as a possible way to create a more inclusive society, where for example social network systems (SNSs) can keep OAs in contact with local communities, create new communities, reduce adverse impact of geographic separation, reduced mobility and lifestyle changes. Objective. As end-users of SNSs, this paper looks at the current state of practice of SNSs for OAs. We explore what OAs think about SNSs, what they want from SNSs and whether these needs are met. Method. Taking a snowballing approach, we examined 51 primary studies on SNSs for OAs. Results. There is a discernible increase in SNSs designed for OAs since 2005, which claim to meet needs such as simplicity, ease of use, privacy and access to useful information. Yet, sustained use over time is unknown. Conclusion. SNSs remain a potential way to reduce the social isolation of OAs, however the extent to which SNSs can replace real human contact is largely unexplored, as is whether SNSs can trigger the creation of new supportive communities.