As a conductor, he concentrated especially on the contemporary French repertoire and Igor Stravinsky's compositions. His reputation as a composer was established in 1925 with a Divertimento (or Cassation) for four wind instruments. With this work, based on Classical forms, he became known as a Czech representative of neoclassicism (Macek 2001).
He wrote the operasAntigone ("Antigona", after Sophocles, 1934) and An Uproar in Efes ("Pozdvižení v Efesu", after Shakespeare, 1943) as well as four symphonies. He died in Prague.
Selected works
Stage works
Small Ballet, to the theme of Pantomime by Vítězslav Nezval, also as a composition for chamber orchestra (1926)
Concertino for Piano with an Accompamment of Wind Instruments (1935)
Concertino for Violin with an Accompaniment of Wind Instruments (1936)
Cocencertino for Violoncello and Orchestra (1939–40)
Chamber music
Divertimento (Cassation) for Flute, Clarinet, Trumpet and Bassoon (1925)
Sonatina for Clarinet and Piano (1929–30)
Trio – Divertimento for Oboe, Clarinet and Bassoon (1935)
Trio for Clarinet, Double Bass and Piano (1936)
Little Funeral Music for Alto, Viola, Violoncello, Double Bass and Piano to Texts of the Psalms and František Halas' Poem "Old Women" (1933, rewritten 1936)
Divertimento for Nonet (1937)
Tre scherzini for pianoforte (1953), according to the original arrangement of the composition for flute and piano from the year 1945
String Quartet No 2 in D-minor (1953)
String Quartet No 3 "In My Father's Memory" (1960)
Sonatina concertante for violoncello and pianoforte (1961)
Wind Quintet (1964)
Trio for Violin, Violoncello and Piano with a song for a female voice to the text of a Psalm
Motives from Antiquity, for a lower male voice and orchestra or piano (1936, arrangement and instrumentation, 1947)
Five Songs to Texts by Jan Amos Komenský for Singing and Piano (1938)
Four Songs to Texts by Jan Neruda for a middle male voice (1939–40)
Choral compositions
The Song of the Multitudes. A fugue for a mixed choir and large orchestra to a text by Josef Hora (1925, instrumentation 1948)
Four Madrigals to Words by Karel Hynek Mácha for a smaller mixed choir, tenor solo and piano (1936)
From the Region of Bagpipers (Z dudáckého kraje). A bouquet of songs after melodies of songs for soprano, tenor, baritone and large orchestra, collected by Karel Weis (1939)
Sacred Carols Sung During Christmas-time (Koledy posvátné v čas vánoční), for a children's or mixed choir with orchestra and organ (1939)
Military Songs from the Záhorácko Region (Vojenské písničky ze Záhorácka), for a male choir unisono, tenor and soprano solo with orchestra (1950)
Four Male Choirs in the Traditional Style to Words by Czech Poets (1966–67)
Macek, Jiří. 2001. "Krejčí, Iša [František]". The New Grove Dictionary of Music and Musicians, second edition, edited by Stanley Sadie and John Tyrrell. London: Macmillan Publishers.