The effect of the carbon source and L-methionine on the ability of Geotrichum candidum to produce volatile sulphur compounds (VSC) was studied. This yeast was cultivated in a synthetic medium supplemented with various carbon sources and L-methionine at different concentrations. Both glycerol and glucose significantly increased VSC production by G. candidum. Unlike the effect on the L-methionine- and 4-methylthio-2-oxobutyric acid-demethiolating activities, the supply of a carbon source had a dramatic effect on the activity of aminotransferase, a key enzyme in L-methionine catabolism. An increase in the initial concentration Of L-methionine resulted in a rise in the production of sulphur compounds (VSC, 4-methylthio-2-oxobutyric acid) but had limited effect on L-methionine-catabolising enzyme activities. Evidence for the existence of a dual effect of the carbon source and L-methionine on VSC biosynthesis was obtained in this study.