Izaly Iosifovich Zemtsovsky (Russian: Изалий Иосифович Земцовский; born February 22, 1936) is a Russian-born American ethnomusicologist.
Zemtsovsky is known in ethnomusicology for his wide range of subjects of study, including the theory of melodic formulas, rhythmic formulas, comparative research of various regions of the world, study of musical universals and the importance of musical data in ethno-genetic reconstructions.
Zemtsovsky has been a lifelong advocate of Russian Soviet musicologist Boris Asafiev's "intonation theory" and contributed to its use at European and American universities.
As a prolific teacher (for several decades he was a professor at the Leningrad State Institute of Theatre, Music and Cinema), he affected the formation of Russian and other ethnic schools of musicologists in former Soviet Union (including Baltic, Caucasian, and Central Asian republics, from the 1990s – independent states) and countries of the Eastern Europe.
In 2011 in recognition of his research activity and prolific teaching Zemtsovsky was awarded the Fumio Koizumi Prize for ethnomusicology.