(12 February 1940 - 15 September 1947) (divorced)
His first marriage, in 1940, was to Austine Byrne McDonnell (1920–1991), a Hearst journalist known as "The Most Magnificent Doll Among American Newspaperwomen". She also screentested for the role of Melanie Wilkes in the motion picture Gone with the Wind. At the time of their marriage, Igor had already been naturalized as a U.S. citizen and they both worked for the Washington Times-Herald. They had no children. Known as Bootsie, she divorced him in 1947 and the next year became the third wife of William Randolph Hearst, Jr. During and after her marriage to Cassini, she wrote "These Charming People", the society column of Washington Times-Herald, under the bylines Austine Cassini and Austine.