The study details the life and work of a nearly forgotten personality in the Hungarian minority history of Slovakia, Ödön Tarján. His contemporaries considered him not only an opposition politician who criticized the government minority and economic policies in the Czechoslovak republic (1918 – 1938), but also an agent of the Hungarian government. He was an outstanding economic expert and an éminence grise of the Hungarian parties who had substantial influence on the administration in Budapest. Despite his Jewish descent, he claimed to belong to the Hungarian national minority.