The National Miners' Union (NMU) was a dual workers' association established in 1928 in the United States of America under the aegis of the Red International of Labour Unions (Profintern), the international trade union authority of the Communist International (Comintern). The union was affiliated with the Trade Union Unity League, American counterpart of the Profintern.
The name of the union was briefly changed to Mine, Oil and Smelter Workers Industrial Union at the group's second convention in 1930, although not long after the organization reverted to its previous title.
The organization conducted controversial and violent strikes during 1931, culminating in a call for a general strike on New Year's Day, 1932. This effort was easily crushed and the NMU effectively broken and powerless until its dissolution at the behest of the Comintern in 1935.