Four Harvard undergraduates gained seats on Lexington's Town Meeting in elections held Monday.

Richard Heller '74 and Benjamin W.Katz '74 won seats on the city's legislative body for the first time, and Robert B.Kent '75 and Daniel I. Small '75 won relection.

All of the seats on the Town Meeting-instead of the usual one-third-were filed Monday. The change was necessary after redistricting by the city's Board of Selectmen raised the number of precincts from six to nine in order to conform with Massachusetts's state guidelines.

Twenty-one members from each new precinct were elected for three, two and one year terms so that each year one-third of the members will come up for reelection as usual.

Kent placed second out of 37 candidates, retaining his three-year seat in the sixth precinct. Kent said that the Town Meeting "is a lot of fun. People are always yelling. People get their views expressed."

Heller, who lost in the 1972 election, placed seventh out of 27 to win a three year seat in the first precinct. Katz said Heller's victory was "the big surprise." Katz finished 14th out of 30 to gain a two year seat in the third precinct.

In the election for the Brookline Town Meeting, Peter A. Koretsky '75 won a three-year seat.

Koretsky said yesterday that the quality of life in Brookline will be his major concern. "I am most concerned with apartment building construction, rent control, property taxes and the schools," he said.

Koretsky led all 11 candidates in the voting.