Relevance of the study «Sinfonia da Requiem» by B. Britten in modern musicology is essential as this work is demonstrative of four interconnected artistic processes: modification and emancipation of the requiem genre, the evolution of Britten’s art, development of European modernistic symphonism, and reception of musical culture of the middle of the XX century at the events of the Second World War. The artistic and historical content of the symphony allows deepening the general scientific ideas about the specifics of the passing of these processes. The scientific novelty of the study is that B. Britten’s «Sinfonia da Requiem» is considered from the angle of revealing direct and indirect features of the requiem genre. To do so, a purposeful genre-intonational analysis of the thematism of the work was employed for the first time. Main objective(s) of the study: to find key musical components (genre features of the requiem and intonational leitmaterial of the composition) and connect them, thus decoding the ideological, genre, and intonational conception of «Sinfonia da Requiem». Methodology. The methodological orientation of the article provides a detailed analysis of the constructive component of music «Sinfonia da Requiem» to determine the semantic content of the composition as an opus belonging to the genre tradition of the requiem, significantly rethought in the compositional practice of the twentieth century. Results of the study. The way of modification and emancipation of genre features of requiem is considered. The ideological and philosophical essence of this genre is formulated. The context of B. Britten’s creation of «Sinfonia da Requiem» is determined — through socio-historical, biographical, and creative factors. The specifics of the embodiment of semantic and constructive features of the requiem genre in the orchestral composition «Sinfonia da Requiem» are determined. The intonational leitmaterial of the composition, which forms the intonational concept of it, is distinguished. Features of transformation of intonational leitmaterial, including genre modulations are traced. A study of the genre-intonational nature of the symphony’s themathism is carried out and variants of semantic interpretation of the main thematic formations are offered. The nature of the genre component of the composition’s dramaturgy is described, in which three groups of genres are traced: military, dancing, and lyrical. The significance of the research lies in supplementing the scientific panorama of English orchestral music of the first half of the twentieth century and in promoting the formation of a more balanced view of the specifics of Britten’s instrumentalism, which was formed and evolved on the basis of exchange with other, including vocal-instrumental genre traditions.