In March 1950, Gregor Lach, his wife and their two children, were deported from Australia back to Germany and back into the care of the International Refugee Organisation (IRO), from which they had left a year earlier. His deportation became a major media event in Australia, in which the ability of the Australian government to safeguard its citizens from undesirable immigrants was debated, and cold war anxieties inflamed. Gregor Lach was one of many who had concealed their Russian identity as a DP in order to avoid repatriation back to the USSR. He had fought with the Soviet Army, deserting into Germany after the war, and registered with the IRO as a Ukrainian from Poland under a new name. But on arrival in Australia, he decided to come clean to the Australian authorities, telling them that he had arrived under a false name, that he was a former Soviet officer, and that he had been in the Communist Party of the USSR. This paper examines the implications of this deportation case for relations with the American-led IRO in postwar Europe, and the wider history of Australia’s prosecution of a cold war immigration policy in Europe after the second world war.