He was the first Secretary of Health under the Philippine Republic. He started as an Assistant Resident Physician in Obstetrics in the Philippine General Hospital (PGH) in 1920. Before becoming Health Secretary, he was in politics as a Member of the 1934 Constitutional Convention and a member of the Philippine Assembly and House of Representatives from 1935-1946. While in Congress, he authored the legislation creating the Department of Health and Public Welfare in 1939. The 1947 reorganization during his administration resulting in the transfer of the Bureau of Welfare and the PGH to the Office of the President and the creation of the Bureau of Hospitals under the Department of Health. The Alabang Vaccine and Serum Laboratory was also transferred from the Institute of Hygiene to the DOH thus making vaccine and sera available at low cost. The joint cooperative project agreement between the DOH and US Public Health Service was signed and implemented within his term. This project involved extensive rehabilitation programs as sanitation, health education and information, food inspection, smallpox vaccination, sanitary engineering, tuberculosis and leprosy control, maternal and child health and nutrition programs.