A royal decree on Tuesday dismissed Education Minister Muhammad Ahmad al-Rashid and replaced him with Abd Allah bin Salih al-Ubaid, chairman of Saudi Arabia's human rights watchdog.
Also fired was Social Affairs Minister Ali bin Ibrahim Namla, who was replaced with Abd al-Muhsin bin Abd al-Aziz al-Akkas, a former boss of the London-based Asharq al-Awsat newspaper.
Culture and Information Minister Fuad Abd al-Sallam Muhammad Farsi and Pilgrimage Minister Iyad bin Amin Madani swapped portfolios.
No explanation was given for the cabinet reshuffle - the second in the oil-rich desert country since April 2004.
The last ministerial change took place when the labour and social affairs portfolio was split into two ministries. King Fahd also carried out a reshuffle in 2003, bringing in five new faces.
Ministers are appointed for four-year terms.