MB ChB Manch 1892, MD (Gold Medal) 1899; MA (hon) Camb 1898; LLD St And 1922.
Marshall studied medicine at Owens College Manchester, where he was a distinguished scholar, gaining a number of scholarships and prizes, and being awarded the Gold Medal for his MD. Marshall was house physician at MRI and was the first honorary research fellow in pharmacology at Owens College before being appointed assistant to the Downing Professor of Medicine at Cambridge. Marshall was professor of materia medica at St Andrews and later at Aberdeen University.