In 1946, he established Pall Corporation. The company's initial focus was on the development of filters for use in aircraft hydraulics. However, in 1959, when Dr. Pall's first wife, Josephine, died of aplastic anemia, he began to work on the "Pall filter". Mrs. Pall had undergone multiple blood transfusions in the course of an illness, which were ultimately unsuccessful. His Pall filter was designed to make blood transfusions significantly safer by filtering out white blood cells, thereby reducing the incidence of transfusion reactions and viral infections.