OpenClinica - OpenClinica is an open source clinical trials software.
GNU Health - GNU Health is a Free/Libre project for health practitioners, health institutions and governments.
Castor EDC - Castor offers you a user-friendly and fully featured application for electronic data collection.
OpenMRS - OpenMRS is a community-developed, open source, enterprise electronic medical record system platform.
FeedbackServer - asp.net survey software Web based and open source software, for purchase or hosted, written in ASP.NET for Nsurvey
drchrono - An EHR built for your specialty: