Demonstrators clashed with police in the Bahraini capital and neighbouring Shiite villages on Tuesday, the sixth anniversary of anti-government protests that were brutally suppressed by the authorities, witnesses said.
"Revolution until victory" and "No forgetting the martyrs", chanted the protesters, many of whom held up pictures of those killed in the crackdown in 2011.
In Manama, protests ended when policemen fired tear gas and stun grenades into the demonstrators to prevent them from reaching the main entrance to the capital.
Activists posted pictures of injured protesters online, but the interior ministry has not published any official statements about the reported demonstrations.
Sunni-ruled Bahrain has been rocked by unrest since March 2011 when authorities backed by Saudi-led forces put down a month of Shiite-led protests demanding democratic reforms.
Since then, hundreds of Shiites have been arrested and put on trial, and others have been stripped of their citizenship.
The country, ruled by the Al-Khalifa dynasty for more than two centuries, has a majority Shiite population which has long complained of marginalisation.