This publication presents the results of the "Dioxins Measurement Programme of North Rhine-Westphalia" which has been initiated and sponsored by the Ministry of the Environment in North Rhine-Westphalia. Only 14 plants emitting more than 1 ng I-TEQ/m3 were found to account for almost the entire quantity emitted annually in North Rhine-Westphalia which according to the measurements amounted to 500 g I-TEQ/a. For about 70% of the more than 50 plants included in the study which were thought to emit increased amounts of dioxins and furans this minitial assumption could not be confirmed; in these cases the concentrations were below 0.1 ng I-TEQ/m3. Thus the entry of dioxins into the atmosphere was caused by few large plants and not by numerous small ones which would have been difficult to monitor. Immediately initiated abatement measures which instantly reduced the entry of PCDD/PCDF into the environment can be considered as the most important success of the programme. Moreover, the results on the measurement programme furnishes important information on the efficiency of waste gas cleaning methods and on the influence which input materials and operating conditions exert on the emissions of dioxins.