On November 25, 1949, David O. Selznick sent this telegram about Anton Karas to Daniel T. O'Shea at Selznick Productions:
...Cannot commence to tell you sensation caused by Karas's zither music in The Third Man. It is rage of England and has already sold more record copies than any other record in entire history of record business in England. It is widest-played dance music in England... Ads here use "Hear Harry Lime Theme," etc. in type dwarfing all other billing. It is one of those unpredictable, tremendous sensations that I cannot expect any of you to understand who have not been here. Entirely unrelated newspaper articles and editorials, even on politics, constantly refer to it. Inevitably, this success will be repeated America if we are prepared for it. We should be able to make fortune out of this music.
Since all films had orchestral scores, it was refreshing and unique. Yet Carol Reed had to resist efforts to keep him from using Karas. The Karas recording was on the radio constantly at all hours.