Available nitrogen contents in biologically aged wine were lower than in young (unaged) wine; this resulted in aslightly lower acetification rate and production with the former. The nitrogen composition of the two vinegars wasvery similar, with l-proline and l-cysteine as the major amino acids. By exception, only the vinegar from the youngwine contained ammonium ion. The ageing process by flor yeast produces urea which is eliminated by the bacteriain the next stage.