Jules Freund (1890 – 1960) was an Hungarian-born American immunologist.
According to the The Journal of Immunology "Jules (Julius) Freund studied in [Budapest] at the Royal Hungarian University. After receiving the degree of M.D. at the age of 23, he served as Medical Interne in the Austrian Army (1913–1914) and was attached to the Department of Hygiene at the University as Assistant. Following the outbreak of war in 1914, he saw service in the Austrian Army and returned to the University in Budapest as Commissioner for Hygiene in the army. He held the post of Assistant Professor in Preventive Medicine, earning the Certificate of Public Health in 1920. In 1922 he went to Hamburg, working in the Department of Hygiene at the Medical School."