The St. Thomas Mount Assembly constituency was one of the 234 state legislative assembly constituencies in Tamil Nadu, a state in southern India. It was in existence for the 1967 and 1971 assembly elections. At that time, this constituency was represented only by the former chief minister of Tamil Nadu M. G. Ramachandran. Later, it was merged with the Alandur assembly constituency from the 1977 assembly election.

No.	Name (Birth–Death)	Term of office		Assembly (Election)	Political party
		Assumed office	Left office
1	M. G. Ramachandran (1917–1987)	15 March 1967	5 January 1971	4th (1967)	Dravida Munnetra Kazhagam
		22 March 1971	14 October 1972	5th (1971)
		17 October 1972	31 January 1976		All India Anna Dravida Munnetra Kazhagam

1971 Tamil Nadu Legislative Assembly election: St. Thomas Mount

Party		Candidate	Votes	%	±%
	DMK	M. G. Ramachandran	65,405	61.11	5.56
	INC(O)	T. L. Raghupathy	40,773	38.10	New
	Independent	M. Varadarajan	850	0.79	New
Majority			24,632	23.01	11.09
Turnout			107,028	67.31	9.26
	DMK hold		Swing	5.56

1967 Madras Legislative Assembly election: St. Thomas Mount

Party		Candidate	Votes	%	±%
	DMK	M. G. Ramachandran	54,106	66.67	New
	INC	T. L. Raghupathy	26,432	32.57	New
	ABJS	K. Kasinathan	613	0.76	New
Majority			27,674	34.10	New
Turnout			81,151	76.57	New
	DMK win (new seat)

• "Statistical reports of assembly elections". Election Commission of India. Archived from the original on 5 October 2010. Retrieved 8 July 2010.

13°01′N 80°11′E / 13.01°N 80.19°E / 13.01; 80.19