First convened in 1973, the Senate's composition and powers are established by the Article 59 of the Constitution of Pakistan. Each four provinces are represented by fourteen senators and eight senators from the tribal areas regardless of population, who serve staggered six-year terms.

The 1973 Constitution provides for a parliamentary form of Government with a bicameral legislature, comprising of the National Assembly and the Senate.

The membership of the Senate, which was originally 45, was raised to 63 in 1977 and to 87 in 1985. The membership of the Senate was again raised from 87 to 100 in 2002.

Since 2003, elections for Senate are being regularly held after every three years with half of the members of Upper House retiring and replaced by newly elected ones.

2003 Senate Elections

Elections to Senate are held in February 2003. Ruling party wins most seats and consolidates its power.

2006 senate elections

Senate elections were held in Pakistan on 6-10 March 2006. Half of the 100 seats in the Senate were up for election with the winning candidates serving six-year terms.

• Pakistan Muslim League (Q) 20 seats

• Muttahida Majlis-e-Amal 10 seats

• Independent 4 seats

• Pakistan People's Party

Parliamentarians 5 seats

• Mutahidda Qaumi Movement 3 seats

• Pakistan Muslim League (N) 1 seat

• Pakhtunkhwa Milli Awami Party 1 seat

• Pakistan Peoples Party 1 seat

• Awami National Party 1 seats

2009 Senate Elections Results

• Pakistan People's Party

Parliamentarians 27 seats

• Pakistan Muslim League (Q) 21 seats

• Independent 13 seats

• Muttahida Majlis-e-Amal 9 seats

• Pakistan Muslim League (N) 7 seats

• Awami National Party 6 seats

• Mutahidda Qaumi Movement 6 seats

• Jamiat Ulema-e-Islam (F) 4 seats

• Balochistan National Party 2 seats

• Jamhoori Wattan Party 1 seat

• National Peoples Party (Pakistan) 1 seat

• Pakhtunkhwa Milli Awami Party 1 seat

• Pakistan Muslim League (F) 1 seat

• Pakistan Peoples Party 1 seat

2012 Senate Elections Results

Pakistan Peoples Party   19 seats

Pakistan Muslim League (N)       8 seats

Awami National Party    7 seats

Pakistan Muslim League (Q)       4 seats

Mutahidda Qaumi Movement 4 seats

Jamiat Ulema-e-Islam 3 seats

Balochistan National Party (Awami) 2 seats

Pakistan Muslim League (F) 1 seat

Independent 5 seats

2015 Senate election results

Pakistan Muslim League (N) 16 seats,

Pakistan People’s Party (PPP) 7 seats

Pakistan Tehreek-e-Insaf  5 seats,

Muttahida Qaumi Movement (MQM) 4 seats

The National Party          3 seats

 Pukhtunkhwa Milli Awami Party 3 seats

Balochistan National Party          1 seat

Jamiat Ulema-e-Islam (F)            1 seat

While an independent candidate also became senator from Balochistan.