This work describes a rapid and sensitive solid-phase microextraction (SPME) method for the isolation and analysis of methyl tert-butyl ether in water samples. Methyl tert-butyl ether was extracted from aqueous solutions using SPME fibre coated with Divinylbenzene/Carboxen/polydimethylsiloxane (30 microm film thickness) and analysed by GC-MS with a Hewlett Packard 6890/5973 system equipped with a capillary column coated with Vocol (30 m x 0.25 mm, 1.5 microm film thickness). Extraction parameters and chromatographic separation conditions were optimised. The developed method showed good analytical performance in terms of precision (RSD between 2% and 8%) and accuracy (mean recovery from 96% to 104%) with a detection limit of 14 ppt. Finally the method was applied to surface, tap and commercial mineral water samples, as well as snow samples collected along a busy road of Bologna town area. The median concentration of methyl tert-butyl ether in all these samples (0.05-0.4 ppb) was well below the maximum aqueous contamination levels in water adopted in the United States (13 ppb).