The Dutch Catholic Mineworkers' Union (Dutch: Nederlandse Katholieke Mijnwerkersbond, NKMB), also known as "Sint Barbara", was a trade union representing coal miners in the Netherlands.
Its main founder was Chris Zielemans, who had previously worked for the United Federation of Christian Trade Unions in Germany.
In 1922, it broke its links with the German federation, in order to provide unemployment insurance in accordance with Dutch law.
In 1925, it was a founding affiliate of the Roman Catholic Workers' Federation, and the following year, it became the NKMB, formally abandoning its interdenominational status.
Long-term leader Frans Dohmen focused on facilitating alternative employment for its members, mostly in and around Limburg.