Lotus corniculatus (bird?s-foot trefoil) and L. uliginosus syn. L. pedunculatus (greater bird?s- foot trefoil) have potential benefits to UK grassland because of the presence of proanthocyanidins, also known as condensed tannins (CTs) in the herbage. We have begun a programme of research to quantify the variation in CT levels and persistence within a number of varieties and selection lines as the first step in the identification of material which can be used in a crossing programme aimed at the development of varieties. We have used a high throughput method of quantifying the level of CTs in herbage of these Lotus species which has revealed significant variation in CT content within and between varieties. A CT content of up to 35 mg/g DM was common among the 20 varieties analysed with some plants showing values of 70 mg/g DM. One variety had a CT content of 150 mg/g DM, which is at a level that could have a negative effect on animal performance. Significant variation in plant persistence was also found with a rhizomatous line (Highgrove) exhibiting high levels of persistence.