Rudolf Eugène Pierre Albertus "Rudy" Ballieux (born 17 September 1930) is a Dutch immunologist.
Ballieux was born on 17 September 1930 in Pekalongan in the Dutch East Indies. After attending the Hogere Burgerschool he studied chemistry and medical science at Utrecht University. He earned his doctor title in 1963 under F.L.J. Jordan.
Ballieux was professor of Clinical Immunology at Utrecht University between 1977 and 1991. He subsequently served another four years as Bijzonder hoogleraar of Psychoimmunophysiology, a bijzonder hoogleraar being a professor paid for by external funds, in his case the Utrecht University Fund. In the later part of his career Ballieux did research on the influence of stress on the immune system.
Ballieux was the first Von Loghem Laureate lecturer of the Dutch Society for Immunology in 1981. He was elected a member of the Royal Netherlands Academy of Arts and Sciences in 1991.