The application and validation of a highly sensitive and specific enzyme immunoassay for the analysis of atrazine residues in natural water samples, plant extracts and soil extracts is described. The EIA is performed on microtitre plates. The range of detection of atrazine analysis lies between approximately 1 ng/l and 10 μg/l. Several synthetic and environmental water samples, plant extracts and soil extracts were analysed with the EIA. A close correspondence was found between the results of the EIA and GC or HPLC measurements, respectively.