A second round of by-elections in the year, and the first time for more than one seat, took place to fill the vacancies that followed the resignations of another three BS Members of Parliament. Chio Cheng Thun and Kow Kee Seng resigned on 8 January 1966 and were expelled from BS six days later. S. T. Bani resigned from both his seat and the party on 9 January 1966. Uncontested victories, not seen since the Legislative and City Council by-elections of 1952 and 1953 respectively, returned and three PAP candidates won without polls conducted.

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
Total seats = 3