Fumonisins are important mycotoxins because they are suspected to cause human and animal toxicoses by the consumption of contaminated corn-based food and feeds. However, with the discovery of fumonisin production in grapes by Aspergillus niger , wine may also be a fumonisin-containing commodity. In the present study, we have developed a simple and quantitative cation-exchange-based purification method for the subsequent isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination of fumonisins in wine. A comparative study of seven different solid-phase extraction (SPE) columns showed that polymeric mixed-mode reversed-phase (RP) cation-exchange columns were superior to classic silica-based cation and mixed-mode cation-exchange columns. A total of 77 wine samples from 13 countries were subsequently tested, and surprisingly, 18 (23%) were found to contain fumonisin B(2) in the range of 1-25 microg/L. These findings were further confirmed by immunoaffinity purification and re-analysis of the positive cation-exchanged extracts.