Lajtha was born in Budapest on June 30, 1892. He studied with Zoltán Kodály
and others, traveling just before World War I to Leipzig and Paris, where he was a student of d'Indy
and became interested in contemporary French development. During the war he enlisted as an artillery gunner, was wounded several times, and suffered lifelong stomach problems from a disease contracted at the front. In the early 1920s Lajtha married and had two sons, both of whom became prominent medical researchers. He taught at Hungary's National Music School, remaining on the faculty there until 1949, and did ethnomusicological research at the country's National Museum of Ethnography, joining Bartók
on song-collecting trips when his health permitted. Bartók
admired Lajtha's compositions, but complained that the younger composer did little to promote his own work.
Lajtha's String Quartet No. 3, Op. 11, won the Coolidge Prize in 1929, inaugurating a period in which his works were frequently performed, both at home and abroad. His works were (and are) issued by the French publisher Alphonse Leduc; they include nine symphonies, ten string quartets, theatrical and film music, piano music, and a variety of smaller works. Lajtha survived World War II in Budapest, hiding out with his family in a university building during the worst of the fighting, and he did much to maintain Hungarian musical life during the war. As Hungary's Communist Party became more powerful, however, he was ideologically suspect, and performances of his works were discouraged. The situation worsened when Lajtha supported the failed Hungarian uprising against the Soviet Union in 1956, but he remained popular abroad, and a French critic reacted to a 1958 Paris performance of his Symphony No. 7, Op. 63 ("Revolution"), by calling him one of the greatest symphonists of the 20th century. Aging and in ill health, but still hard at work, Lajtha was given a passport in 1961. He delivered a lecture at the Academie Française in 1962. Returning from a trip to collect folk music, Lajtha died of a heart attack on February 16, 1963.