The Caerphilly by-election of 15 June 1968 was held after the death of Labour MP Ness Edwards.
The seat was very safe, having been won by Labour at the United Kingdom general election, 1966 by over 21,000 votes
- Labour chose Alfred Evans to defend their seat, who was a councillor
- Nationalist party Plaid Cymru stood Philip Williams, who at the time was teaching at University College, Aberystwyth
- The Conservatives chose Robert Williams
- Peter Sadler was the choice of the Liberal Party association
Result of the previous general election
Result of the by-election