The official Bahrain News Agency announced the High Court of Appeals acquitted 21 medics tied to unrest at the Salmaniya medical complex in 2011. Chief Prosecutor Mehanna al-Shaiji said two defendants, who went unnamed, lost their appeal.
The British government said it welcomed the news as a sign Bahrain was starting to take reform measures seriously.
"This decision goes some way to addressing these issues," a government statement read. "We expect all outstanding cases before the courts relating to peaceful political protest to be dealt with quickly and transparently, ensuring due legal process is followed."
An independent commission of inquiry examining the government's crackdown to the Shiite-led uprising offered a series of reforms to the Sunni monarchy. The government said it's committed to that agenda despite lingering criticism of its rights situation.
The Salmaniya medical complex in Manama was raided by Bahraini security forces in March 2011 as part of the regime's crackdown.
At least 50 people were killed during the uprising.