Istvan Kertesz (August 28, 1929 – April 16, 1973) was a Hungarian conductor.

Kertesz was born in Budapest, and studied music at the Ferenc Liszt Academy there, where his teachers included Zoltán Kodály. He was influenced by Bruno Walter and Otto Klemperer, then director of the Budapest Opera.

He left Hungary in 1956 and settled in West Germany, becoming music director at the Augsburg Opera, and the the Cologne Opera. In Cologne, he conducted the first German performance of Britten's Billy Budd.

He was principal conductor of the London Symphony Orchestra from 1965 to 1968. He was appointed conductor of the Bamberger Symphoniker in 1973 and shortly thereafter drowned while swimming off the coast of Israel while on a concert tour.