Carbamate-type herbicides can be detected by means of a tllin-layer chromatographic-enzymatic inhibition technique with bovine liver esterase. The minimum quantities detected were in the range of 3-100 ,ug for the N-pl~enylcarlxmates and 5-30 ,q for the thiolcarbamates, depending on pretreatment. Under normal assay conditions and after bromine treatment N-phenylcarbamutes show a more intense colour. No activation of the e&erase takes place, however, and it is supposed that this phenomenon is due to a reaction between enzymatic degradation products and Fast Blue Salt B. After UV irradiation these substances are real inhibitors. The thiolcarbamates studied show inhibitory activity against bovine liver esterasc. After UV irradiation only Diallate and Triallate are stronger inhibitors, while Eptam, Vcrnolatc, and Pebulate remain unaffected. 13romine treatment has only a slight effect. Kinetic studies with Eptam and Vernolate show that thiolcarbamates are degraded to other antiesterase substances and it is supposed that the degradation products arc the sulphosides and/or sulpl~ones.