In Saudi Arabia, people staged a rally to call for the withdrawal of Saudi troops from Bahrain. Egyptians also held one of the biggest rallies since President Hosni Mubarak's fall.
Saudi Arabia sent 1,000 troops last month to Bahrain, a Sunni Muslim monarchy, to help contain pro-democracy protests led by the countries Shi'ite majority.
In Syria, people showed protest against President Bashar al-Assad and security forces opened fire on thousands of demonstrators in the southern city of Deraa.
Friday has become a peak day of protest for many Arabs since popular demands for freedom, democracy and an end to corruption began in Tunisia in 2010 and spread across the region. Yemen people also showed protest against its President Ali Abdullah Saleh and demanded his resignation.