Uku Masing lived in Dorpat (now Tartu, Estonia). After studying theology, Uku Masing became a professor at the Dorpat Theology Faculty, teaching Semitic languages and the Old Testament. When German troops occupied Dorpat in July 1941, Uku Masing and his wife Eha saw Jews being persecuted and murdered by the German occupying forces. The couple decided to help. They hid a former student of Masing’s, Isidor Levin (1919–2018), in their home and obtained false papers for him.
In 1942 German security police and SD officers searched the Masings’ house. Isidor Levin was arrested and deported to the German Reich. He survived various prisons and concentration camps and returned to Estonia in 1945.
After the war, Uku Masing was a member of a commission for the prosecution of war crimes, and collected evidence for the murder of Jews in Estonia.
In 1969 Eha and Uku Masing were honored in Yad Vashem as Righteous Among the Nations.