Vostřák initiated his work in the generic Romantic style. Beginning with his cycle of songs entitled While Falling Asleep, he turned to dodecaphony and techniques proceeding from this particular principle. In the following years Vostřák employed the style known by the general title of New Music. During the late 1960s and early 1970s he was widely engaged in composing electronic music which he sometimes combined with live performers. During the first stage of his career Vostřák wrote several successful operas and ballets. The following phase featured almost exclusively concert compositions with a predominance of instrumental music. Many of Vostřák's works are regarded as pioneering achievements in this field. As a result of Czechoslovakia's official cultural policy in the 1970s and 1980s, particularly in relation to the kind of music composed by Vostřák at that time, the composer had steadily decreasing possibilities for introducing his compositions at home, even though he had succumbed to national pressure by resorting to the use of phony titles for some of his works.
