In the article the method of the analysis of zearalenone in the aqueous environment using GC-MS chromatography with electron ionization (EI) is described. The separation of zearalenone from the aqueous matrix was performed by means of solid phase extraction with the use of Supelclean^TM ENVI-18 tubes. Extraction efficiency was determined by the analysis of deionized and tap water samples of volume ranging from 100 to 500 cm³, and zearalenone concentrations varying from 50 to 200 ng/dm³. Chromatography analysis was preceded by the derivatization of samples via silylation reaction using a ternary mixture of BSTFA/TMCS/DTE. The developed method enabled us to determine the content of zearalenone in aqueous environment at a concentration level from 0.3 to 0.5 ng/dm³, with the repeatability of the analysis 4-8%. The efficiency of the extraction exceeded 62% and depended on the investigated matrix and the volume of analyzed sample. In the final stage of the study the analysis of 500 cm³ samples of natural water collected in the Upper Silesia Region was performed. The determined concentration of zearalenone was in the range from 0 to 3.2 ng/dm³, depending on the character of the analyzed sample.