Milk supplied to a dairy plant in Brescia City (Northern Italy) was found to be contaminated by dioxin like PCBs at levels above the European (EU) action limit (2 pg WHO-TEQ/g fat). As a consequence, 14 dairy farms were sampled individually, in order to identify and possibly eliminate the source of contamination. All the farms were located in Brescia or just nearby, an area that is characterized by a strong industrialization. Four out of the 14 farms showed contamination levels above the legal maximum limit set by European Commission at 5.5 pg WHO-TEQ/g fat for the sum of dioxins and DL-PCBs. Concentrations of 8.16, 6.83, 5.71 and 5.65 pg WHO-TEQ/g fat were detected. In the three most polluted farms, cow ration was substituted with feed coming from uncontaminated areas and the time needed to reduce milk pollution was evaluated. In all the three farms, contamination levels dropped below the EU legal limit after only 1 month from the removal of the pollution source. In each sampled farm, DL-PCBs were the major contributors to the total WHO-TEQ level, with percentages up to 87% in the most contaminated one. PCB 126 WHO-TEQ value explained by itself large part of this contamination, and its decrease was fundamental for the reduction of milk contamination levels. This study provides an example of an on-field successful emergency intervention that succeeded in decontamination of dairy cows, allowing a fast restart of their production activity.