Born in Poland, he studied Semitic Studies at the University of Vienna and at the Sorbonne. After war broke out in 1939, he was interned by the French in a warehouse, but from where he managed to escape in 1942 in the United States. He received the position of a professor at the University of California, Los Angeles ( UCLA). Until his death at the age of 100 years, he was professor emeritus at the University. Leslau specialized in the study of Semitic languages of Ethiopia. He published numerous works on almost all äthiosemitischen languages. Between 1946 and 1976 he made several research trips to Ethiopia.
- Emigrant from the German Empire at the time of National Socialism
- Guggenheim Fellow
- University teachers ( University of California, Los Angeles)
- Born in 1906
- Died in 2006