Integrating Information Systems (IS) is essential to support shared care. Many different integration approaches have been implementation through the years. This paper summarises studies examining approaches to integrate patient data from different IS. The literature was systematically reviewed in the last decade (1995-2005) to identify articles that mention patient records, computers and data integration or sharing. Of 3124 articles, 84 were included describing 58 distinct projects. Most of the recent projects were regional. More recently significantly more IS are integrating referral letters and extending to primary care. We conclude that patient information is becoming more accessible as there are more integrated IS which are more likely to involve primary care and a wider range of patient level data.