1,3-Butadiene is used in the production of synthetic rubber and is also a widespread environmental pollutant, produced by car exhaust, heating and cigarette smoke. According to IARC it is probably carcinogenic to humans. A method was developed and validated for the quantification in human urine of 1,2-dihydroxybutyl mercapturic acid, a butacliene metabolite for which the American Conference of Governmental Hygienists suggests a biological exposure index of 2500 mu g/L. Solid phase extraction was used for analyte extraction and HPLC-MS/MS for detection. The calibration range from 20 to 2500 mu g/L required the use of polynomial calibration curves, and the performance of the analytical method was tested according to an international validation guideline. Accuracy was never less than 85%, precision always higher than 15% and the LOD 3.6 mu g/L The method was applied to 33 non-smokers, non-occupationally exposed to butadiene, and gave urinary concentrations between 16 and 599 mu g/L. (C) 2009 Elsevier B.V. All rights reserved.