Aims: Brettanomyces/Dekkera bruxellensis is a particularly troublesome wine spoilage yeast. This work was aimed at characterizing its behaviour in terms of growth and volatile compound production in red wine. Methods and Results: Sterile red wines were inoculated with 5 x 10(3) viable cells ml(-1) of three B. bruxellensis strains and growth and volatile phenol production were followed for 1 month by means of plate counts and gas chromatography-mass spectrometry (GC-MS) respectively. Maximum population levels generally attained 10(6)-10(7) colony forming units (CFU) ml(-1) and volatile phenol concentrations ranged from 500 to 4000 mu g l(-1). Brettanomyces bruxellensis multiplication was also accompanied by the production of organic acids (from C-2 to C-10), short chain acid ethyl-esters and the 'mousy off-flavour' component 2-acetyl-tetrahydropyridine. Conclusions: Different kinds of 'Brett character' characterized by distinct metabolic and sensory profiles can arise in wine depending on the contaminating strain, wine pH and sugar content and the winemaking stage at which contamination occurs. Significance and Impact of the Study: We identified new chemical markers that indicate wine defects caused by B. bruxellensis. Further insight was provided into the role of some environmental conditions in promoting wine spoilage.