Now, a look on 2 piece swimsuits in Tamil films.
I think Manjula is the first major heroine to act in a bikini. The film is Dr. Siva (1975)
Jayalakshmi (I hope I got her name right. Somebody help). The yesteryear vamp did many bikini parts, like in Kasethan Kadavulada (1972). ‘Indru vantha inba mayakkam’ is the song.
Deepa - Antharangam (1975)
Sri Devi - Priya (1978)
Madhavi - She wore bikini in so many films. Tic Tic Tic (1981), Viduthalai (1986) to name a few.
Amala - She made a sensation in Jeeva (1988). Till then she has been acting only in homely roles. She runs on the beach wearing a bikini for a few secs.
Sindhu - Inaintha Kaigal (1990)
Kushboo - Naattukkoru Nallavan (1991)
Yuvarani - Minmini Poochigal (1993). For a good part of more than 10 min.
Mumtaj - Monisha En Monalisa (2000)
Kiran - Winner (2003)
Silk Smitha, Disco Shanthi, Anuradha, Kuyili and some more vamps - There are so many films.