Chlorsulfuron (chemical name : 2-Chloro-N-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-aminocarbonyl-benzenesulfonamide) is a herbicidally active ingredient which shows effect against susceptible weeds already at such low rates like 5-20g active ingredient per hectare. In the here reported trials metabolism in several sensitive cultivated plants and weeds have been analysed using ^{14}C-labelled active ingredient. The uptake of chlorsulfuron by leaves or the root system is good in all plants species, and translocation takes place either symplasmatically or apoplasmatically. Metabolism takes place in all investigated plant species by development of hydrophile suhstances in roots and shoots. Decomposition of chlorsulfuron in roots and shoots of tolerant species (Triticum aestivum and Hordeum vulgare) to polare substances takes place quantitatively faster and quicker than in susceptible species (Beta vulgaris and Matricaria chamomilla).