The invention relates to a method to increase production of itaconic acid in a micro-organism by inhibiting the expression or functioning of the enzyme itaconyl-CoA transferase, itaconyl-CoA hydratase (citramalyl-CoA hydrolyase; EC 4.2.1.56) and/or citramalyl-CoA lyase. Also embodied are micro-organisms, preferably Aspergillus s terreus or Aspergillus niger, in which said enzyme is inhibited.