A second round of by-elections in the year took place to fill the vacancies following the resignations of another three Barisan Members of Parliament. Chio Cheng Thun and Kow Kee Seng resigned on 8 January 1966 and were expelled from Barisan six days later. S. T. Bani resigned from both his seat and the party on 9 January 1966. All three PAP candidates won uncontested, something not witnessed since the Legislative and City Council by-elections of 1952 and 1953 respectively.

Writ of election: 23 February 1966 [Wed]
Nomination day: 1 March 1966 [Tue]
Members swearing-in: 21 April 1966 [Thu]

Electorate: 36,573

Election deposit: $500

Chua Chu Kang Crawford Paya Lebar

General Election 1963
By-Election 1965
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Next: By-Elections November 1966
By-Elections 1967
General Election 1968