The amino acid composition of the different field bean protein isolates shows a good correspondence. In relation to casein the content of the whole essential amino acids is low. In the first line the low content of methionine and cystine limits the biological value of this proteins. The content of lysine is relatively high. The enzymatic in vitro-hydrolysis results in a corresponding availability of the amino acids between the field bean proteins and casein. The digestibility is very good, the biological value with less than 50 relatively low. Apart from the low content of the sulphur containing amino acids the amino acid composition of the spun field bean protein/casein(I:I) fibers corresponds with the calculated value; the enzymatic availability of the fibers is also comparable with casein. The digestibility in the nitrogen balance test is very good and the biological value of the fiber corresponds with that of casein.