The New York Times has called him "the most venerated conductor since Arturo Toscanini."

His father was also one of the great conductors of the 20th Century, the Austrian Erich Kleiber (1890-1956). At the time Carlos was born, Erich had been Generalmusikdirektor of the Berlin State Opera, and had presented the world premiere of Alban Berg's opera "Wozzeck." In 1934, to protest Hitler's National Socialist government, he resigned and emigrated to South America.

Carlos was interested in music from an early age, and learned the basics from his family. But Erich opposed it as his son's career. When Carlos started his university studies in 1949 in Zürich, the chosen field was chemistry. He rebelled against this choice, returned to Buenos Aires at the end of his first year, and resumed studying music.

He returned to Europe in 1952 to become a repétiteur (rehearsal coach) and a stage assistant at the Theater am Gärtnerplatz in Munich. He made his conducting debut in Millöcker's "Gasparone" in 1954. He attained another repetiteur position in 1956 at the Deutsche Oper am Rhein in Düsseldorf and was promoted to conductor in 1958. From 1964 to 1966 he was a conductor at the Zürich Opera, then First Conductor at the Württemberg State Theater in Stuttgart (1966-1968). From 1968 to 1978 he was a conductor at the Bavarian State Opera in Munich.

During this period he made notable guest appearances. His British debut was conducting "Wozzeck" at the Edinburgh Festival in 1966. His Vienna debut was leading "Tristan und Isolde" in 1973; he debuted at Bayreuth conducting the same Wagner opera. In 1974 he appeared for the first time in Both Covent Garden (London) and La Scala (Milan), in both cases conducting Richard Strauss's "Der Rosenkavalier." His American debut vehicle was Verdi's "Otello," at San Francisco.

In the meantime he also started appearing as a conductor of orchestral concerts, leading a few of the greatest orchestras of the world, including the Chicago Symphony, the Vienna Philharmonic, and the Berlin Philharmonic.

After he gave up his position in Munich, he did not enter into any other permanent relationship with an orchestra or opera house. Instead, he adopted the practice of making rare guest appearances. On those occasions, he requires that the management grant him extra rehearsal time. At rehearsal he is a tireless perfectionist, with a remarkable intensity both in this part of the job and in performance itself. He produces performances of absolutely polished execution and a sense of having stripped away everything but the composer's purest intentions.

He has also released only a few recordings, but each one is considered a masterpiece of interpretation. His repertory includes some Beethoven, Brahms, and Mozart symphonies and overtures, the operas already mentioned (excluding the Millöcker work), Johann Strauss's "Die Fledermaus" and a few waltzes and other lighter works, which he has performed on Vienna Philharmonic New Year's Concerts. Some of his opera productions and a generous three-hour Unitel release featuring his rehearsal and conducting technique are available on video.

A very private man, he avoids public appearances and press interviews. He became a naturalized Austrian citizen in 1980. ~ Joseph Stevenson