The flavour of Agaricus bisporus was studied by comparing the results obtained in chemical and organoleptic analysis of the same extract. The natural (-)-form of 1-octen-3-ol had a stronger flavour than the (+)-form and was the most important aroma component. Nucleotides, amino-acids and carbohydrates also contributed significantly. Benzaldehyde, benzyl alcohol, 1-octen-3-one, n-butyric and isovaleric acids as well as low-boiling volatiles contributed less to the flavour. A synergistic effect of nucleotides, carbohydrates and (-1-octen-3-ol on the flavour was not observed.