Plants of birdsfoot trefoil (Lotus corniculatus) and alfalfa (Medicago sativa) were transformed by Agrobacterium with binary vectors harbouring genes that code either for wild-type and g-zein:KDEL, or for b-zein:KDEL. The maize seed storage proteins g-zein and b-zein are rich in sulphur amino acids and our long-term goal was to improve alfalfa and birdsfoot trefoil forage quality. Significant levels of zeins were detected in leaves of birdsfoot trefoil transformants, ranging up to 0.055 per cent and to 0.30 per cent of total extractable protein for g-zein and b-zein:KDEL, respectively. In leaves of alfalfa, g-zein:KDEL expression level was up to 0.026 per cent of the total extractable protein. Coexpression of the g-zein and b-zein genes in tobacco proved a useful strategy to increase the content of zein polypeptides and at the moment we are analysing L. corniculatus plants derived from the cross of parents expressing different zein genes.