Eugen Warming was a frequent visitor to foreign universities, e.g. a travel to Strasbourg and Paris in 1876 and another to Göttingen, Jena, Bonn, Strasbourg and Paris in 1880. He participated in several Scandinavian Scientist Conferences between 1868 and 1916 and in the similar German meeting in Breslau in 1874. He joined the International Botanical Congresses in Amsterdam 1877, in Vienna 1905 and in Brussels 1910 and was president of the ‘Association internationale des botanistes‘ (1913). He attended the Linnaeus celebration in Uppsala 1907 and the Darwin celebration in London 1908. He was honorary fellow of the Royal Society in London, was elected member of the Royal Swedish Academy of Sciences in 1885 and honorary member of the Danish Botanical Society. He was a corresponding member of the botanical section of the French Academy of Sciences.