Methods for the determination of toxic pyrrolizidine alkaloids in plants and foods are described with emphasis on the important aspects of sample extraction and clean-up and the now preferred determination by liquid chromatography-mass spectrometry. The efficiencies of different extraction solvents and methods are described, as are the methods of reduction of N-oxides. Appropriate liquid chromatography-mass spectrometry conditions are tabulated. This concise review is intended to guide analysts towards adopting a more unified and reliable approach to the analysis of these important toxins.