Isa Krejci was the son of philosopher Frantisek Krejci. He studied history and musicology at Charles University and concurrently piano playing with A. Sima and composition with K. B. Jirak at the Prague Conservatoire. He also attended a master class at that school, studying composition under V. Novak and conducting with V. Talich. After gaining his fist experiences of a conductor in the Slovak National Theatre in Bratislava (1928 - 32) and in Prague s National Theatre (1933 - 34), Krejci worked as a music producer in the Czechoslovak Radio (1934 - 45) and a conductor of the Orchestral Association in Prague (1936 - 45). In the following years he was head of an opera company in Olomouc, from 1958 onwards a dramaturgist of the National Theatre Opera Compeny ln Prague and during the 1964 - 65 season head of an opera company in Ceské Budéjovice. His dramaturgy there was noted for the successful staging of several new operas.
Although Isa Krejci may be described as a modest, one might even say, shy man who never tried publicly to promote his own works, his music has come to be very popular indeed, mostly thanks to its indiputable artistic qualities.
As far as Krejci's compositional type is concerned, he is known to have proceeded from Mozartian style whose harmonics was enriched by dissonances. His melodics is straightfonvard and simple, condensed but invariably well-defined and witty, resembling folk musicality. Isa Krejci' s compasitions, predominantly retaining the classical forms, are transparent, charming, lively or even wanton in rapid sequences, meditative in slow-flowing ones, while the artist was no stranger to tragic positions either. His most successful opuses include the opera An Uproar in Efes, based on Shakespeare's Comedy of Errors, orchestral works from the 1950s as well as a number of chamber compositions, among which Krejci minor Cassation for Flute, Clarinet, Trumpet and Bassoon, written in the early days of his career, stands out as one of his most popular pieces.