From 1998 to 1999, an extremely intensive dioxin measuring campaign has been performed at the sinterplants of Sidmar. More than 500 measurements have been made. Several hypotheses and adsorbents have been tested for the reduction of the dioxins. Process control improvements and the use of burnt lime then allowed reducing the dioxin emissions by 85 % . For a further decrease, it was decided to build an industrial coal injection installation at the sinterplants. The present reduction of the dioxin emissions is more than 95 % and will reach 97 % in 2001.