Oemr is a project mainly written in ..., it's free.
Electronic health record
Welcome to OEMR!!!
OEMR is a free Open source, Practice management, Electronic Medical Records, prescription writing and medical billing application for Unix-like systems (Linux, UNIX, and BSD systems), Microsoft systems, Mac OS X and other platforms.
Setup documentation can be found in the INSTALL file, and extensive documentation can be found on the OEMR wiki at: http://www.openmedsoftware.org/