The aroma-active compounds potentially important to Parmigiano Reggiano cheese were studied using a dynamic headspace-gas chromatography-olfactometry (GC-O-DH) technique. The aroma contribution was evaluated by both Osme and AEDA technique. The Osme values were. based on a 10 point scale, while the flavour dilution values of AEDA were obtained by sequentially reducing the sample size at a fixed purge gas volume. In general, aroma compounds with high Osme values also had high FD values. Among the aroma compounds identified in Parmigiano, Reggiano, cheese, acetaldehyde, 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, ethyl butanoate, ethyl hexanoate, ethyl octanoate, methional, dimethyl trisulphide, diacetyl, and 2,6-dimethylpyrazine were considered the most odour-potent. Copyright (C) 2003 John Wiley Sons, Ltd.