VistA (Enterprise Electronic Health Record)
OpenVistA and WorldVistA are two varieties of the largest and most robust CCHIT-approved electronic health record platform in the public domain. They are GPL licensed, are based on the US Veterans Administration health record system, and can be installed as an integrated database, server, and client system. See the detailed download and installation instructions for OpenVistA and WorldVistA, or visit Vistapedia for other instructions. Also see the Ultimate Server with OpenVistA EHR.