The European Parliament (Representation) Act 2003 (c.7) was an Act of the Parliament of the United Kingdom. The long title is "An Act to make provision enabling alterations to be made to the total number of Members of the European Parliament to be elected for the United Kingdom and to their distribution between the electoral regions; to make provision for and in connection with the establishment of an electoral region including Gibraltar for the purposes of European Parliamentary elections; and for connected purposes."

The Act made provision for a reduction in the number of Members of the European Parliament who represent the United Kingdom (see Treaty of Nice). Gibraltar was enfranchised by adding it to the South West England constituency after taking the British Government to the European Court of Justice.

The number of seats each region was allocated is as follows:

• East Midlands 6
• Eastern 8
• London 10
• North East 4
• North West 10
• South East 11
• South West 7
• West Midlands 8
• Yorkshire and the Humber 7
• Scotland 8
• Wales 5
• Northern Ireland 3

The addition of Gibraltar to the English constituency gave rise to some problems concerning the jurisdiction of the Courts of England and Wales and the Courts of Gibraltar over which would have power to hear election petitions, this can be seen by some of the discussions held in the Standing Committee during the bill stage.^[1]

The European Union (Withdrawal) Act 2018 repealed the act on 31 January 2020.