Five years later (1924), Jaisohn went legally bankrupt due to his political engagement and had to resume medical profession to make a living. At age 62, he became a student again at the University of Pennsylvania to renew his medical knowledge. Since then, he published five research articles in the medical journals specialized in pathology. During World War II, he volunteered as a physical examination officer with the belief that the victory of the U.S. would bring freedom to Korea.