HOSxP, an open source hospital information system (GNU GPL). Designed and developed by health care practitioners with first-hand experience, the software aims to ease healthcare workflow of health centers, from small sanitariums to big central hospitals. The software is already in production use in over 70 hospitals across Thailand, with many hospitals currently testing/reviewing the software. Source code (on SourceForge). Download. Wiki. Forum.
The server software can be run either on Linux or Windows. A client runs on Windows.