Aim of study: It is generally accepted that since the end of the Secon
d World War, English has become the main language in the medical field
in Switzerland, but scarcely any objective data are available on the
development of this process in this country. The aim of the present st
udy was to analyze the frequency of the different languages in the lit
erature references in articles published in the Swiss Medical Weekly o
ver the past 75 years, with special attention to the possible differen
ces existing between articles originating in German-speaking Switzerla
nd and French-speaking Switzerland. Methods: The language of publicati
on of 47160 literature references cited in 2489 original articles publ
ished in the Swiss Medical Weekly between 1920 and 1995 was establishe
d. The 1730 articles published in German contained 32607 assessable re
ferences; the 759 articles published in French contained 14553 assessa
ble references. Results: The percentages of literature references in G
erman, French and English cited in the articles written in German were
, respectively, 83.6%, 9.1% and 5.9% in 1920; 68.6%, 7.2% and 18.3% in
1945; 30.7%, 5.6% and 61.9% in 1970; 11.3%, 1.5% and 86.7% in 1995. T
he percentages of literature references in French, German and English
cited in the articles written in French were, respectively, 61.1%, 31.
8% and 4.0% in 1920; 30.6%, 39.3% and 26.5% in 1945; 19.8%, 9.6% and 6
9.7% in 1970; 7.4%, 2.4% and 90.0% in 1995. Conclusions: (1) Between 1
945 and 1995 the percentage of literature references in English has in
creased continuously, while the percentages of references in German an
d French have decreased. (2) English replaced German as the main langu
age of medicine towards 1955 in French-speaking Switzerland and toward
s 1965 in German-speaking Switzerland. (3) During the whole period stu
died (1920-1995), French-speaking authors cited publications in German
more frequently than German-speaking authors cited publications in Fr
ench. (4) The evolution of the relative importance of the languages in
German-speaking Switzerland is very similar to that previously descri
bed in Germany and Austria. (5) In French-speaking Switzerland, on the
other hand, the evolution of the relative importance of the different
languages differs very considerably from that previously described in
France.