Due to a rapid increase in aging population, demand for personalized health care increases proportionally. Personalized patient data can be a helpful way of catering the needs and requirements of elderly people staying at home. Indirectly, it can be a manner of providing better eHealth services according to their needs. Another interesting aspect of providing better personalized eHealth services is to make patient information systems interoperable. Interoperability of eHealth systems is an issue of great concern to current research and development but in this study, we focus on patient information systems. Like in some other European countries, introduction of open source platform to achieve interoperability and personalization of patient information system could save money for health care organizations and make the procedure easier in Sweden also. The purpose of this study is to identify what standards are available for interoperability and what are the benefits and challenges of introducing open source systems for achieving personalized interoperable patient information systems (PIPIS). In light of this investigation, author has identified the benefits and challenges of introducing OSS for achieving PIPIS. Author has also made several recommendations regarding the challenges identified. / In the name of ALLAH, the most gracious and merciful. I extend my gratitude to the beautiful creator of this beautiful universe that He made for us to conquer. Without the love of my parents this thesis report could never be possible for me to write. All my love and care is for them which no one else can share. I thank Mr. Hans Kyhlbäck whose supervision is a source of inspiration for doing this study. He is definitely the best supervisor to work with. In the end, I would like to thank my friends and colleagues whose help just kept me going despite of many hurdles that I faced.