After the war he covered the Nuremberg Trials in 1946 and, along with Ernst von Schenck, provided analytical commentary for the memoirs of Alfred Rosenberg,[1] Nazi Germany's chief racial theoretician, who was executed in October of that year.

As a correspondent for the leading French evening paper Le Soir, Lang also attended a variety of sporting events after reporting on the 1948 Winter Olympics at St. Moritz, especially alpine skiing and cycling.

It was such an exciting event that Serge Lang was convinced afterwards it was time to greatly enlarge the horizon of alpine ski racing mostly limited to central Europe during the winter season.

In December 1965, L'Équipe launched the first (unofficial) European ski circuit named "Trophée de L'Equipe", which was won by France's Marielle Goitschel and Austria's Karl Schranz.

Lang, after discussing it with some of his friends Bob Beattie, the US Alpine Director, and Honoré Bonnet, Head Coach of the French Ski Team, during a downhill training session of the famous "Hahnenkamm" races at Kitzbühel, Austria, in January 1966, decided that it should become a world tour.

The President of the International Ski Federation (FIS), Marc Hodler from Switzerland, agreed to support the new event which he personally presented to the press in Chile.

Lang lived his later years in Riehen, Switzerland, and apparently died of a heart attack in Sternenberg, Haut-Rhin, France while writing his memoirs in November 1999.