A simple, highly sensitive and reliable microfunnel magnetic stirring-assisted dispersive liquid-liquid microextraction method (MF-MSA-DLLME) was developed based on the derivatization of mutagen X in aqueous samples and determined using gas chromatography with electron capture (GC-ECD). The effects of different variables on the extraction efficiency were investigated and optimized. The calibration curve showed good linearity in the concentration range of 0.05-400 gL(-1) (r(2) = 0.998) and precision (RSD = 5.0%). Under optimum conditions, the limit of detection (LOD) and the limit of quantification in drinking water were 0.015 and 0.05 mu g L-1, respectively. The developed method was successfully applied for the determination of six Mutagen X (MX) in real samples.