Chanting slogans against the Saudi authorities, the demonstrators turned out in Qatif late on Sunday to condemn the regime’s suppression of dissent.
Late last month, Saudi forces killed three people and wounded several others while searching for an activist wanted by the regime.
The kingdom’s oil-rich Eastern Province has been rocked by anti-regime protests since last year.
Since February 2011, protesters have held demonstrations on an almost regular basis in Saudi Arabia, mainly in Qatif and Awamiyah in Eastern Province, primarily calling for the release of all political prisoners, freedom of expression and assembly, as well as an end to widespread discrimination.
However, the demonstrations have turned into protests against the repressive Al Saud regime, especially since November 2011, when Saudi security forces killed five protesters and injured many others in the province.