3-Amino-1,2,4-triazole (amitrole) is a widely used pesticide, with many difficulties to be analyzed at the regulatory level in drinking water, because its high solubility in water. This paper describes a simple and fast method for the simultaneous determination of amitrole and atrazin-2-hydroxy, principal degradation product of s-triazines, by capillary zone electrophoresis. Separation and determination of these herbicides in water samples was performed in 0.02 mol l(-1) phosphate buffer at pH 3.2. The method allows determination of the amitrole and atrazin-2-hydroxy in water samples in concentration lower than 100 mug l(-1). The detection limits using a previous preconcentration step of amitrole in Alberche River (Comunidad Autónoma de Madrid, Spain) and drinking water spiked samples was of 4 mug l(-1).